package executor

import (
	"context"
	"fmt"
	"log/slog"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"
	"time"

	"github.com/thepeterstone/claudomator/internal/storage"
	"github.com/thepeterstone/claudomator/internal/task"
)

// capturingHandler is a slog.Handler that records log records for assertions.
type capturingHandler struct {
	mu      sync.Mutex
	records []slog.Record
}

func (h *capturingHandler) Enabled(_ context.Context, _ slog.Level) bool { return true }
func (h *capturingHandler) Handle(_ context.Context, r slog.Record) error {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.records = append(h.records, r)
	return nil
}
func (h *capturingHandler) WithAttrs(attrs []slog.Attr) slog.Handler { return h }
func (h *capturingHandler) WithGroup(name string) slog.Handler       { return h }

func (h *capturingHandler) hasMessageContaining(substr string) bool {
	h.mu.Lock()
	defer h.mu.Unlock()
	for _, r := range h.records {
		if strings.Contains(r.Message, substr) {
			return true
		}
	}
	return false
}

// failingStore wraps a real DB but returns an error for UpdateTaskState calls.
type failingStore struct {
	*storage.DB
	updateStateErr error
}

func (f *failingStore) UpdateTaskState(id string, newState task.State) error {
	return f.updateStateErr
}

// mockRunner implements Runner for testing.
type mockRunner struct {
	mu       sync.Mutex
	calls    int
	delay    time.Duration
	err      error
	exitCode int
	onRun    func(*task.Task, *storage.Execution) error
}

func (m *mockRunner) Run(ctx context.Context, t *task.Task, e *storage.Execution) error {
	m.mu.Lock()
	m.calls++
	cb := m.onRun
	m.mu.Unlock()

	if m.delay > 0 {
		select {
		case <-time.After(m.delay):
		case <-ctx.Done():
			return ctx.Err()
		}
	}
	if cb != nil {
		return cb(t, e)
	}
	if m.err != nil {
		e.ExitCode = m.exitCode
		return m.err
	}
	return nil
}

func (m *mockRunner) callCount() int {
	m.mu.Lock()
	defer m.mu.Unlock()
	return m.calls
}

func testStore(t *testing.T) *storage.DB {
	t.Helper()
	dbPath := filepath.Join(t.TempDir(), "test.db")
	db, err := storage.Open(dbPath)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { db.Close() })
	return db
}

func makeTask(id string) *task.Task {
	now := time.Now().UTC()
	return &task.Task{
		ID: id, Name: "Test " + id,
		Agent:    task.AgentConfig{Type: "claude", Instructions: "test"},
		Priority:  task.PriorityNormal,
		Retry:     task.RetryConfig{MaxAttempts: 1, Backoff: "linear"},
		Tags:      []string{},
		DependsOn: []string{},
		State:     task.StateQueued,
		CreatedAt: now, UpdatedAt: now,
	}
}

func TestPickAgent_PrefersLessActiveAgent(t *testing.T) {
	status := SystemStatus{
		ActiveTasks: map[string]int{"claude": 3, "gemini": 1},
		RateLimited: map[string]bool{"claude": false, "gemini": false},
	}
	if got := pickAgent(status); got != "gemini" {
		t.Errorf("expected gemini (fewer active tasks), got %s", got)
	}
}

func TestPickAgent_SkipsRateLimitedAgent(t *testing.T) {
	status := SystemStatus{
		ActiveTasks: map[string]int{"claude": 0, "gemini": 5},
		RateLimited: map[string]bool{"claude": true, "gemini": false},
	}
	if got := pickAgent(status); got != "gemini" {
		t.Errorf("expected gemini (claude rate limited), got %s", got)
	}
}

func TestPickAgent_FallsBackWhenAllRateLimited(t *testing.T) {
	status := SystemStatus{
		ActiveTasks: map[string]int{"claude": 2, "gemini": 5},
		RateLimited: map[string]bool{"claude": true, "gemini": true},
	}
	// Falls back to least active regardless of rate limit.
	if got := pickAgent(status); got != "claude" {
		t.Errorf("expected claude (fewer active tasks among all), got %s", got)
	}
}

func TestPickAgent_TieBreakPrefersFirstAlpha(t *testing.T) {
	status := SystemStatus{
		ActiveTasks: map[string]int{"claude": 2, "gemini": 2},
		RateLimited: map[string]bool{"claude": false, "gemini": false},
	}
	got := pickAgent(status)
	if got != "claude" && got != "gemini" {
		t.Errorf("unexpected agent %q on tie", got)
	}
}

func TestPool_Submit_TopLevel_GoesToReady(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("ps-1") // no ParentTaskID → top-level
	store.CreateTask(tk)

	if err := pool.Submit(context.Background(), tk); err != nil {
		t.Fatalf("submit: %v", err)
	}

	result := <-pool.Results()
	if result.Err != nil {
		t.Errorf("expected no error, got: %v", result.Err)
	}
	if result.Execution.Status != "READY" {
		t.Errorf("status: want READY, got %q", result.Execution.Status)
	}

	got, _ := store.GetTask("ps-1")
	if got.State != task.StateReady {
		t.Errorf("task state: want READY, got %v", got.State)
	}
}

func TestPool_Submit_Subtask_GoesToCompleted(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("sub-1")
	tk.ParentTaskID = "parent-99" // subtask
	store.CreateTask(tk)

	if err := pool.Submit(context.Background(), tk); err != nil {
		t.Fatalf("submit: %v", err)
	}

	result := <-pool.Results()
	if result.Err != nil {
		t.Errorf("expected no error, got: %v", result.Err)
	}
	if result.Execution.Status != "COMPLETED" {
		t.Errorf("status: want COMPLETED, got %q", result.Execution.Status)
	}

	got, _ := store.GetTask("sub-1")
	if got.State != task.StateCompleted {
		t.Errorf("task state: want COMPLETED, got %v", got.State)
	}
}

func TestPool_Submit_Failure(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{err: fmt.Errorf("boom"), exitCode: 1}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("pf-1")
	store.CreateTask(tk)
	pool.Submit(context.Background(), tk)

	result := <-pool.Results()
	if result.Err == nil {
		t.Fatal("expected error")
	}
	if result.Execution.Status != "FAILED" {
		t.Errorf("status: want FAILED, got %q", result.Execution.Status)
	}
}

// TestPool_UpdateTaskState_DBError_IsLoggedAndResultDelivered verifies that
// when UpdateTaskState returns an error, the error is logged with structured
// context (taskID, state) and the execution result is still sent to resultCh.
func TestPool_UpdateTaskState_DBError_IsLoggedAndResultDelivered(t *testing.T) {
	db := testStore(t)
	store := &failingStore{DB: db, updateStateErr: fmt.Errorf("db write failed")}

	handler := &capturingHandler{}
	logger := slog.New(handler)

	runner := &mockRunner{err: fmt.Errorf("runner error")}
	runners := map[string]Runner{"claude": runner}
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("dberr-1")
	db.CreateTask(tk)

	if err := pool.Submit(context.Background(), tk); err != nil {
		t.Fatalf("submit: %v", err)
	}

	select {
	case result := <-pool.Results():
		// Result must still arrive despite the DB error.
		if result == nil {
			t.Fatal("expected non-nil result")
		}
		if result.TaskID != tk.ID {
			t.Errorf("taskID: want %q, got %q", tk.ID, result.TaskID)
		}
	case <-time.After(5 * time.Second):
		t.Fatal("timed out waiting for result — result not delivered despite DB error")
	}

	if !handler.hasMessageContaining("failed to update task state") {
		t.Error("expected 'failed to update task state' log entry, but none found")
	}
}

func TestPool_Submit_Timeout(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{delay: 5 * time.Second}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("pt-1")
	tk.Timeout.Duration = 50 * time.Millisecond
	store.CreateTask(tk)
	pool.Submit(context.Background(), tk)

	result := <-pool.Results()
	if result.Execution.Status != "TIMED_OUT" {
		t.Errorf("status: want TIMED_OUT, got %q", result.Execution.Status)
	}
}

func TestPool_Submit_Cancellation(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{delay: 5 * time.Second}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	ctx, cancel := context.WithCancel(context.Background())
	tk := makeTask("pc-1")
	store.CreateTask(tk)
	pool.Submit(ctx, tk)

	time.Sleep(20 * time.Millisecond)
	cancel()

	result := <-pool.Results()
	if result.Execution.Status != "CANCELLED" {
		t.Errorf("status: want CANCELLED, got %q", result.Execution.Status)
	}
}

func TestPool_Cancel_StopsRunningTask(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{delay: 5 * time.Second}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("cancel-1")
	store.CreateTask(tk)
	pool.Submit(context.Background(), tk)
	time.Sleep(20 * time.Millisecond) // let goroutine start

	if ok := pool.Cancel("cancel-1"); !ok {
		t.Fatal("Cancel returned false for a running task")
	}

	result := <-pool.Results()
	if result.Execution.Status != "CANCELLED" {
		t.Errorf("status: want CANCELLED, got %q", result.Execution.Status)
	}
}

func TestPool_Cancel_UnknownTask_ReturnsFalse(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	if ok := pool.Cancel("nonexistent"); ok {
		t.Error("Cancel returned true for unknown task")
	}
}

// TestPool_QueuedWhenAtCapacity verifies that Submit enqueues a task rather than
// returning an error when the pool is at capacity. Both tasks should eventually complete.
func TestPool_QueuedWhenAtCapacity(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{delay: 100 * time.Millisecond}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(1, runners, store, logger)

	tk1 := makeTask("queue-1")
	store.CreateTask(tk1)
	if err := pool.Submit(context.Background(), tk1); err != nil {
		t.Fatalf("first submit: %v", err)
	}

	// Second submit must succeed (queued) even though pool slot is taken.
	tk2 := makeTask("queue-2")
	store.CreateTask(tk2)
	if err := pool.Submit(context.Background(), tk2); err != nil {
		t.Fatalf("second submit: %v — expected task to be queued, not rejected", err)
	}

	// Both tasks must complete.
	for i := 0; i < 2; i++ {
		r := <-pool.Results()
		if r.Err != nil {
			t.Errorf("task %s error: %v", r.TaskID, r.Err)
		}
	}
}

// logPatherMockRunner is a mockRunner that also implements LogPather,
// and captures the StdoutPath seen when Run() is called.
type logPatherMockRunner struct {
	mockRunner
	logDir       string
	capturedPath string
}

func (m *logPatherMockRunner) ExecLogDir(execID string) string {
	return filepath.Join(m.logDir, execID)
}

func (m *logPatherMockRunner) Run(ctx context.Context, t *task.Task, e *storage.Execution) error {
	m.mu.Lock()
	m.capturedPath = e.StdoutPath
	m.mu.Unlock()
	return m.mockRunner.Run(ctx, t, e)
}

// TestPool_Execute_LogPathsPreSetBeforeRun verifies that when the runner
// implements LogPather, log paths are set on the execution before Run() is
// called — so they land in the DB at CreateExecution time, not just at
// UpdateExecution time.
func TestPool_Execute_LogPathsPreSetBeforeRun(t *testing.T) {
	store := testStore(t)
	runner := &logPatherMockRunner{logDir: t.TempDir()}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("lp-1")
	store.CreateTask(tk)
	if err := pool.Submit(context.Background(), tk); err != nil {
		t.Fatalf("submit: %v", err)
	}
	result := <-pool.Results()

	runner.mu.Lock()
	captured := runner.capturedPath
	runner.mu.Unlock()

	if captured == "" {
		t.Fatal("StdoutPath was empty when Run() was called; expected pre-set path")
	}
	if !strings.HasSuffix(captured, "stdout.log") {
		t.Errorf("expected stdout.log suffix, got: %s", captured)
	}
	// Path in the returned execution record should match.
	if result.Execution.StdoutPath != captured {
		t.Errorf("execution StdoutPath %q != captured %q", result.Execution.StdoutPath, captured)
	}
}

// TestPool_Execute_NoLogPather_PathsEmptyBeforeRun verifies that a runner
// without LogPather doesn't panic and paths remain empty until Run() sets them.
func TestPool_Execute_NoLogPather_PathsEmptyBeforeRun(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{} // does NOT implement LogPather
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("nolp-1")
	store.CreateTask(tk)
	if err := pool.Submit(context.Background(), tk); err != nil {
		t.Fatalf("submit: %v", err)
	}
	result := <-pool.Results()
	if result.Err != nil {
		t.Fatalf("unexpected error: %v", result.Err)
	}
}

func TestPool_ConcurrentExecution(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{delay: 50 * time.Millisecond}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(3, runners, store, logger)

	for i := 0; i < 3; i++ {
		tk := makeTask(fmt.Sprintf("cc-%d", i))
		store.CreateTask(tk)
		if err := pool.Submit(context.Background(), tk); err != nil {
			t.Fatalf("submit %d: %v", i, err)
		}
	}

	for i := 0; i < 3; i++ {
		result := <-pool.Results()
		if result.Execution.Status != "READY" {
			t.Errorf("task %s: want READY, got %q", result.TaskID, result.Execution.Status)
		}
	}

	if runner.callCount() != 3 {
		t.Errorf("calls: want 3, got %d", runner.callCount())
	}
}

func TestWithFailureHistory_NoFailures_ReturnsUnchanged(t *testing.T) {
	tk := makeTask("no-fail")
	result := withFailureHistory(tk, nil, nil)
	if result != tk {
		t.Error("expected same pointer when no prior executions")
	}
}

func TestWithFailureHistory_WithError_ReturnsUnchanged(t *testing.T) {
	tk := makeTask("err-case")
	result := withFailureHistory(tk, nil, fmt.Errorf("db error"))
	if result != tk {
		t.Error("expected same pointer when ListExecutions errors")
	}
}

func TestWithFailureHistory_InjectsFailedHistory(t *testing.T) {
	tk := makeTask("with-fail")
	tk.Agent.Instructions = "do the work"

	execs := []*storage.Execution{
		{ID: "e1", Status: "FAILED", ErrorMsg: "sandbox: uncommitted changes", StartTime: time.Now()},
		{ID: "e2", Status: "COMPLETED", ErrorMsg: "", StartTime: time.Now()}, // not a failure, should be ignored
	}
	result := withFailureHistory(tk, execs, nil)

	if result == tk {
		t.Fatal("expected a new task copy, got same pointer")
	}
	if !strings.Contains(result.Agent.SystemPromptAppend, "Prior Attempt History") {
		t.Errorf("expected history header in SystemPromptAppend, got: %q", result.Agent.SystemPromptAppend)
	}
	if !strings.Contains(result.Agent.SystemPromptAppend, "sandbox: uncommitted changes") {
		t.Errorf("expected error message in SystemPromptAppend, got: %q", result.Agent.SystemPromptAppend)
	}
	// COMPLETED execution should not appear
	if strings.Contains(result.Agent.SystemPromptAppend, "e2") {
		t.Errorf("COMPLETED execution should not appear in history")
	}
	// Original instructions unchanged
	if result.Agent.Instructions != "do the work" {
		t.Errorf("instructions should be unchanged, got: %q", result.Agent.Instructions)
	}
}

func TestWithFailureHistory_PreservesExistingSystemPrompt(t *testing.T) {
	tk := makeTask("with-prompt")
	tk.Agent.SystemPromptAppend = "existing prompt"

	execs := []*storage.Execution{
		{ID: "e1", Status: "FAILED", ErrorMsg: "some error", StartTime: time.Now()},
	}
	result := withFailureHistory(tk, execs, nil)

	if !strings.Contains(result.Agent.SystemPromptAppend, "Prior Attempt History") {
		t.Error("expected history prepended")
	}
	if !strings.Contains(result.Agent.SystemPromptAppend, "existing prompt") {
		t.Error("expected existing prompt preserved")
	}
	// History must come BEFORE the existing prompt
	histIdx := strings.Index(result.Agent.SystemPromptAppend, "Prior Attempt History")
	existIdx := strings.Index(result.Agent.SystemPromptAppend, "existing prompt")
	if histIdx > existIdx {
		t.Error("history should be prepended before existing system prompt")
	}
}

func TestPool_FailureHistoryInjectedOnRetry(t *testing.T) {
	store := testStore(t)

	var capturedPrompt string
	runner := &mockRunner{}
	runner.onRun = func(t *task.Task, _ *storage.Execution) error {
		capturedPrompt = t.Agent.SystemPromptAppend
		return nil
	}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("retry-hist")
	store.CreateTask(tk)

	// Simulate a prior failed execution.
	store.CreateExecution(&storage.Execution{
		ID: "prior-exec", TaskID: tk.ID,
		StartTime: time.Now(), EndTime: time.Now(),
		Status: "FAILED", ErrorMsg: "prior failure reason",
	})

	if err := pool.Submit(context.Background(), tk); err != nil {
		t.Fatalf("submit: %v", err)
	}
	<-pool.Results()

	if !strings.Contains(capturedPrompt, "prior failure reason") {
		t.Errorf("expected prior failure in system prompt, got: %q", capturedPrompt)
	}
}

func TestPool_RecoverStaleRunning(t *testing.T) {
	store := testStore(t)
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, map[string]Runner{"claude": &mockRunner{}}, store, logger)

	// Create a task already in RUNNING state (simulating a crashed server).
	tk := makeTask("stale-1")
	tk.State = task.StateRunning
	store.CreateTask(tk)

	// Add an open execution record (no end time, status RUNNING).
	store.CreateExecution(&storage.Execution{
		ID: "exec-stale-1", TaskID: tk.ID,
		StartTime: time.Now().Add(-5 * time.Minute),
		Status:    "RUNNING",
	})

	pool.RecoverStaleRunning(context.Background())

	// Execution record should be closed as FAILED.
	execs, _ := store.ListExecutions(tk.ID)
	if len(execs) == 0 || execs[0].Status != "FAILED" {
		t.Errorf("execution status: want FAILED, got %+v", execs)
	}
	if execs[0].ErrorMsg == "" {
		t.Error("expected non-empty error message on recovered execution")
	}

	// Task should be re-queued for retry and complete.
	select {
	case result := <-pool.Results():
		if result.TaskID != tk.ID {
			t.Errorf("unexpected task in results: %s", result.TaskID)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("timed out waiting for stale RUNNING task to be re-queued and run")
	}
	recovered, err := store.GetTask(tk.ID)
	if err != nil {
		t.Fatalf("get task: %v", err)
	}
	// Top-level tasks (no parent) go to READY after a successful run.
	if recovered.State != task.StateReady {
		t.Errorf("state after re-queue: want READY, got %q", recovered.State)
	}
}

func TestPool_RecoverStaleQueued_ResubmitsToPool(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, map[string]Runner{"claude": runner}, store, logger)

	// Create a task already in QUEUED state (persisted from before a server restart).
	tk := makeTask("stale-queued-1")
	tk.State = task.StateQueued
	store.CreateTask(tk)

	pool.RecoverStaleQueued(context.Background())

	// Wait for the pool to pick it up and complete it.
	select {
	case result := <-pool.Results():
		if result.TaskID != tk.ID {
			t.Errorf("unexpected task in results: %s", result.TaskID)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("timed out waiting for stale QUEUED task to complete")
	}

	got, err := store.GetTask(tk.ID)
	if err != nil {
		t.Fatalf("get task: %v", err)
	}
	if got.State != task.StateCompleted && got.State != task.StateReady {
		t.Errorf("state: want COMPLETED or READY, got %q", got.State)
	}
	if runner.callCount() != 1 {
		t.Errorf("runner call count: want 1, got %d", runner.callCount())
	}
}

func TestPool_RecoverStaleQueued_SkipsNonQueuedTasks(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, map[string]Runner{"claude": runner}, store, logger)

	// PENDING task should NOT be resubmitted.
	tk := makeTask("pending-1")
	tk.State = task.StatePending
	store.CreateTask(tk)

	pool.RecoverStaleQueued(context.Background())
	time.Sleep(50 * time.Millisecond)

	if runner.callCount() != 0 {
		t.Errorf("runner should not have been called for PENDING task, got %d calls", runner.callCount())
	}
}

func TestPool_ActivePerAgent_DeletesZeroEntries(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner, "gemini": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("apa-1")
	store.CreateTask(tk) // Agent.Type = "claude"
	pool.Submit(context.Background(), tk)
	<-pool.Results()

	pool.mu.Lock()
	_, exists := pool.activePerAgent["claude"]
	pool.mu.Unlock()

	if exists {
		t.Error("activePerAgent should not have a zero-count entry for claude after task completes")
	}
}

func TestPool_RateLimited_StaleEntryCleaned(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	// Inject a stale rate-limit entry (deadline already passed).
	pool.mu.Lock()
	pool.rateLimited["claude"] = time.Now().Add(-1 * time.Minute)
	pool.mu.Unlock()

	// Submit a task — the execute() path reads rateLimited during classification.
	tk := makeTask("rl-stale-1")
	store.CreateTask(tk)
	pool.Submit(context.Background(), tk)
	<-pool.Results()

	pool.mu.Lock()
	_, exists := pool.rateLimited["claude"]
	pool.mu.Unlock()

	if exists {
		t.Error("stale rate-limit entry should be deleted after deadline passes")
	}
}

// TestPool_Submit_TopLevel_NoSubtasks_GoesReady verifies that a top-level task
// with no subtasks still transitions to READY after successful execution.
func TestPool_Submit_TopLevel_NoSubtasks_GoesReady(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	tk := makeTask("no-subtasks-1") // no ParentTaskID, no subtasks
	store.CreateTask(tk)

	if err := pool.Submit(context.Background(), tk); err != nil {
		t.Fatalf("submit: %v", err)
	}

	result := <-pool.Results()
	if result.Err != nil {
		t.Errorf("expected no error, got: %v", result.Err)
	}
	if result.Execution.Status != "READY" {
		t.Errorf("status: want READY, got %q", result.Execution.Status)
	}
	got, _ := store.GetTask(tk.ID)
	if got.State != task.StateReady {
		t.Errorf("task state: want READY, got %v", got.State)
	}
}

// TestPool_Submit_TopLevel_WithSubtasks_GoesBlocked verifies that when a
// top-level task finishes successfully but has subtasks, it transitions to
// BLOCKED (waiting for subtasks) rather than READY.
func TestPool_Submit_TopLevel_WithSubtasks_GoesBlocked(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	parent := makeTask("parent-with-subtasks")
	store.CreateTask(parent)

	// Create a subtask in the store but do NOT submit it.
	sub := makeTask("sub-of-parent")
	sub.ParentTaskID = parent.ID
	store.CreateTask(sub)

	if err := pool.Submit(context.Background(), parent); err != nil {
		t.Fatalf("submit: %v", err)
	}

	result := <-pool.Results()
	if result.Err != nil {
		t.Errorf("expected no error, got: %v", result.Err)
	}
	if result.Execution.Status != "BLOCKED" {
		t.Errorf("status: want BLOCKED, got %q", result.Execution.Status)
	}
	got, _ := store.GetTask(parent.ID)
	if got.State != task.StateBlocked {
		t.Errorf("task state: want BLOCKED, got %v", got.State)
	}
}

// TestPool_Submit_LastSubtask_UnblocksParent verifies that when the last
// remaining subtask completes, the parent task transitions from BLOCKED to READY.
func TestPool_Submit_LastSubtask_UnblocksParent(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	// Parent starts BLOCKED (waiting for subtasks).
	parent := makeTask("unblock-parent-1")
	parent.State = task.StateBlocked
	store.CreateTask(parent)

	// First subtask already completed.
	sub1 := makeTask("unblock-sub-1a")
	sub1.ParentTaskID = parent.ID
	sub1.State = task.StateCompleted
	store.CreateTask(sub1)

	// Second (last) subtask — the one we submit.
	sub2 := makeTask("unblock-sub-1b")
	sub2.ParentTaskID = parent.ID
	store.CreateTask(sub2)

	if err := pool.Submit(context.Background(), sub2); err != nil {
		t.Fatalf("submit: %v", err)
	}

	result := <-pool.Results()
	if result.Err != nil {
		t.Errorf("expected no error, got: %v", result.Err)
	}
	if result.Execution.Status != "COMPLETED" {
		t.Errorf("subtask status: want COMPLETED, got %q", result.Execution.Status)
	}

	// Parent must now be READY.
	got, err := store.GetTask(parent.ID)
	if err != nil {
		t.Fatalf("get parent: %v", err)
	}
	if got.State != task.StateReady {
		t.Errorf("parent state: want READY, got %v", got.State)
	}
}

// TestPool_Submit_NotLastSubtask_ParentStaysBlocked verifies that when a subtask
// completes but another sibling subtask is still running, the parent stays BLOCKED.
func TestPool_Submit_NotLastSubtask_ParentStaysBlocked(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	parent := makeTask("blocked-parent-2")
	parent.State = task.StateBlocked
	store.CreateTask(parent)

	// First subtask still RUNNING — not done yet.
	sub1 := makeTask("blocked-sub-2a")
	sub1.ParentTaskID = parent.ID
	sub1.State = task.StateRunning
	store.CreateTask(sub1)

	// Second subtask — the one we submit.
	sub2 := makeTask("blocked-sub-2b")
	sub2.ParentTaskID = parent.ID
	store.CreateTask(sub2)

	if err := pool.Submit(context.Background(), sub2); err != nil {
		t.Fatalf("submit: %v", err)
	}

	<-pool.Results()

	// Parent must remain BLOCKED because sub1 is still RUNNING.
	got, err := store.GetTask(parent.ID)
	if err != nil {
		t.Fatalf("get parent: %v", err)
	}
	if got.State != task.StateBlocked {
		t.Errorf("parent state: want BLOCKED, got %v", got.State)
	}
}

// TestPool_Submit_ParentNotBlocked_NoTransition verifies that completing a subtask
// does not change the parent's state when the parent is not BLOCKED.
func TestPool_Submit_ParentNotBlocked_NoTransition(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	// Parent is already READY (not BLOCKED).
	parent := makeTask("ready-parent-3")
	parent.State = task.StateReady
	store.CreateTask(parent)

	sub1 := makeTask("ready-sub-3a")
	sub1.ParentTaskID = parent.ID
	store.CreateTask(sub1)

	if err := pool.Submit(context.Background(), sub1); err != nil {
		t.Fatalf("submit: %v", err)
	}

	<-pool.Results()

	// Parent must remain READY — no spurious state transition.
	got, err := store.GetTask(parent.ID)
	if err != nil {
		t.Fatalf("get parent: %v", err)
	}
	if got.State != task.StateReady {
		t.Errorf("parent state: want READY, got %v", got.State)
	}
}

// minimalMockStore is a standalone Store implementation for unit-testing Pool
// methods that do not require a real SQLite database.
type minimalMockStore struct {
	mu              sync.Mutex
	tasks           map[string]*task.Task
	executions      map[string]*storage.Execution
	stateUpdates    []struct{ id string; state task.State }
	questionUpdates []string
	subtasksFunc    func(parentID string) ([]*task.Task, error)
	updateExecErr   error
	updateStateErr  error
}

func newMinimalMockStore() *minimalMockStore {
	return &minimalMockStore{
		tasks:      make(map[string]*task.Task),
		executions: make(map[string]*storage.Execution),
	}
}

func (m *minimalMockStore) GetTask(id string) (*task.Task, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	t, ok := m.tasks[id]
	if !ok {
		return nil, fmt.Errorf("task %q not found", id)
	}
	return t, nil
}
func (m *minimalMockStore) ListTasks(_ storage.TaskFilter) ([]*task.Task, error) { return nil, nil }
func (m *minimalMockStore) ListSubtasks(parentID string) ([]*task.Task, error) {
	if m.subtasksFunc != nil {
		return m.subtasksFunc(parentID)
	}
	return nil, nil
}
func (m *minimalMockStore) ListExecutions(_ string) ([]*storage.Execution, error) { return nil, nil }
func (m *minimalMockStore) CreateExecution(e *storage.Execution) error              { return nil }
func (m *minimalMockStore) UpdateExecution(e *storage.Execution) error {
	return m.updateExecErr
}
func (m *minimalMockStore) UpdateTaskState(id string, newState task.State) error {
	if m.updateStateErr != nil {
		return m.updateStateErr
	}
	m.mu.Lock()
	m.stateUpdates = append(m.stateUpdates, struct{ id string; state task.State }{id, newState})
	if t, ok := m.tasks[id]; ok {
		t.State = newState
	}
	m.mu.Unlock()
	return nil
}
func (m *minimalMockStore) UpdateTaskQuestion(taskID, questionJSON string) error {
	m.mu.Lock()
	m.questionUpdates = append(m.questionUpdates, questionJSON)
	m.mu.Unlock()
	return nil
}
func (m *minimalMockStore) UpdateTaskSummary(taskID, summary string) error        { return nil }
func (m *minimalMockStore) AppendTaskInteraction(taskID string, _ task.Interaction) error {
	return nil
}
func (m *minimalMockStore) UpdateTaskAgent(id string, agent task.AgentConfig) error { return nil }

func (m *minimalMockStore) lastStateUpdate() (string, task.State, bool) {
	m.mu.Lock()
	defer m.mu.Unlock()
	if len(m.stateUpdates) == 0 {
		return "", "", false
	}
	u := m.stateUpdates[len(m.stateUpdates)-1]
	return u.id, u.state, true
}

func newPoolWithMockStore(store Store) *Pool {
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	return &Pool{
		maxConcurrent:  2,
		runners:        map[string]Runner{"claude": &mockRunner{}},
		store:          store,
		logger:         logger,
		activePerAgent: make(map[string]int),
		rateLimited:    make(map[string]time.Time),
		cancels:        make(map[string]context.CancelFunc),
		resultCh:       make(chan *Result, 4),
		workCh:         make(chan workItem, 4),
		doneCh:         make(chan struct{}, 2),
		Questions:      NewQuestionRegistry(),
	}
}

// TestHandleRunResult_SharedPath verifies that handleRunResult correctly
// classifies runner errors and transitions task state via the store.
func TestHandleRunResult_SharedPath(t *testing.T) {
	t.Run("generic error sets FAILED", func(t *testing.T) {
		store := newMinimalMockStore()
		pool := newPoolWithMockStore(store)
		tk := makeTask("hrr-fail")
		store.tasks[tk.ID] = tk

		exec := &storage.Execution{ID: "e1", TaskID: tk.ID, Status: "RUNNING"}
		ctx := context.Background()

		pool.handleRunResult(ctx, tk, exec, fmt.Errorf("something broke"), "claude")

		if exec.Status != "FAILED" {
			t.Errorf("exec.Status: want FAILED, got %q", exec.Status)
		}
		if exec.ErrorMsg != "something broke" {
			t.Errorf("exec.ErrorMsg: want %q, got %q", "something broke", exec.ErrorMsg)
		}
		_, state, ok := store.lastStateUpdate()
		if !ok || state != task.StateFailed {
			t.Errorf("expected UpdateTaskState(FAILED), got state=%v ok=%v", state, ok)
		}
		result := <-pool.resultCh
		if result.Err == nil || result.Execution.Status != "FAILED" {
			t.Errorf("unexpected result: %+v", result)
		}
	})

	t.Run("nil error top-level no subtasks sets READY", func(t *testing.T) {
		store := newMinimalMockStore()
		pool := newPoolWithMockStore(store)
		tk := makeTask("hrr-ready")
		store.tasks[tk.ID] = tk

		exec := &storage.Execution{ID: "e2", TaskID: tk.ID, Status: "RUNNING"}
		ctx := context.Background()

		pool.handleRunResult(ctx, tk, exec, nil, "claude")

		if exec.Status != "READY" {
			t.Errorf("exec.Status: want READY, got %q", exec.Status)
		}
		_, state, ok := store.lastStateUpdate()
		if !ok || state != task.StateReady {
			t.Errorf("expected UpdateTaskState(READY), got state=%v ok=%v", state, ok)
		}
		result := <-pool.resultCh
		if result.Err != nil || result.Execution.Status != "READY" {
			t.Errorf("unexpected result: %+v", result)
		}
	})

	t.Run("nil error subtask sets COMPLETED", func(t *testing.T) {
		store := newMinimalMockStore()
		pool := newPoolWithMockStore(store)
		parent := makeTask("hrr-parent")
		parent.State = task.StateBlocked
		store.tasks[parent.ID] = parent

		tk := makeTask("hrr-sub")
		tk.ParentTaskID = parent.ID
		store.tasks[tk.ID] = tk

		exec := &storage.Execution{ID: "e3", TaskID: tk.ID, Status: "RUNNING"}
		ctx := context.Background()

		pool.handleRunResult(ctx, tk, exec, nil, "claude")

		if exec.Status != "COMPLETED" {
			t.Errorf("exec.Status: want COMPLETED, got %q", exec.Status)
		}
		result := <-pool.resultCh
		if result.Err != nil || result.Execution.Status != "COMPLETED" {
			t.Errorf("unexpected result: %+v", result)
		}
	})

	t.Run("timeout sets TIMED_OUT", func(t *testing.T) {
		store := newMinimalMockStore()
		pool := newPoolWithMockStore(store)
		tk := makeTask("hrr-timeout")
		store.tasks[tk.ID] = tk

		exec := &storage.Execution{ID: "e4", TaskID: tk.ID, Status: "RUNNING"}
		ctx, cancel := context.WithCancel(context.Background())
		cancel() // make ctx.Err() == context.Canceled

		// Simulate deadline exceeded by using a deadline-exceeded context.
		dctx, dcancel := context.WithDeadline(context.Background(), time.Now().Add(-time.Second))
		defer dcancel()

		pool.handleRunResult(dctx, tk, exec, context.DeadlineExceeded, "claude")

		if exec.Status != "TIMED_OUT" {
			t.Errorf("exec.Status: want TIMED_OUT, got %q", exec.Status)
		}
		_ = ctx
		<-pool.resultCh
	})
}

// TestPool_LoadBalancing_OverridesAgentType verifies that load balancing picks
// from registered runners, overriding any pre-set Agent.Type on the task.
func TestPool_LoadBalancing_OverridesAgentType(t *testing.T) {
	store := testStore(t)
	runner := &mockRunner{}
	runners := map[string]Runner{"claude": runner}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(2, runners, store, logger)

	// Task has a non-existent agent type; load balancing should route to "claude".
	tk := makeTask("lb-override")
	tk.Agent.Type = "super-ai"
	store.CreateTask(tk)

	if err := pool.Submit(context.Background(), tk); err != nil {
		t.Fatalf("submit: %v", err)
	}

	result := <-pool.Results()
	if result.Err != nil {
		t.Fatalf("expected success (load balancing overrides agent type), got: %v", result.Err)
	}
	if runner.callCount() != 1 {
		t.Errorf("expected claude runner to be called once, got %d", runner.callCount())
	}
}

// TestPool_SpecificAgent_SkipsLoadBalancing verifies that if a specific
// registered agent is requested (claude or gemini), it is used directly
// and load balancing (pickAgent) is skipped.
func TestPool_SpecificAgent_SkipsLoadBalancing(t *testing.T) {
	store := testStore(t)
	claudeRunner := &mockRunner{}
	geminiRunner := &mockRunner{}
	runners := map[string]Runner{
		"claude": claudeRunner,
		"gemini": geminiRunner,
	}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(4, runners, store, logger)

	// Inject 2 active tasks for gemini, 0 for claude.
	// pickAgent would normally pick "claude".
	pool.mu.Lock()
	pool.activePerAgent["gemini"] = 2
	pool.mu.Unlock()

	tk := makeTask("specific-gemini")
	tk.Agent.Type = "gemini"
	store.CreateTask(tk)

	if err := pool.Submit(context.Background(), tk); err != nil {
		t.Fatalf("submit: %v", err)
	}

	<-pool.Results()

	if geminiRunner.callCount() != 1 {
		t.Errorf("expected gemini runner to be called once, got %d", geminiRunner.callCount())
	}
	if claudeRunner.callCount() != 0 {
		t.Errorf("expected claude runner to NOT be called, got %d", claudeRunner.callCount())
	}
}

// TestPool_SpecificAgent_PersistsToDB verifies that if a specific agent
// is requested, it is persisted to the database before the task runs.
func TestPool_SpecificAgent_PersistsToDB(t *testing.T) {
	store := testStore(t)
	geminiRunner := &mockRunner{}
	runners := map[string]Runner{
		"gemini": geminiRunner,
	}
	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
	pool := NewPool(4, runners, store, logger)

	tk := makeTask("persist-gemini")
	tk.Agent.Type = "gemini"
	store.CreateTask(tk)

	if err := pool.Submit(context.Background(), tk); err != nil {
		t.Fatalf("submit: %v", err)
	}

	<-pool.Results()

	// Check the task in the database.
	reloaded, err := store.GetTask(tk.ID)
	if err != nil {
		t.Fatalf("get task: %v", err)
	}
	if reloaded.Agent.Type != "gemini" {
		t.Errorf("expected agent type gemini in DB, got %q", reloaded.Agent.Type)
	}
}