package executor

import (
	"context"
	"errors"
	"log/slog"
	"os"
	"strings"
	"testing"
	"time"

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

// depTask returns a task with the given DependsOn and state, using the same
// shape makeTask() produces (see executor_test.go) so it satisfies
// task.Validate-adjacent expectations (non-nil Tags/DependsOn slices etc).
func depTask(id string, dependsOn []string, state task.State) *task.Task {
	tk := makeTask(id)
	if dependsOn == nil {
		dependsOn = []string{}
	}
	tk.DependsOn = dependsOn
	tk.State = state
	return tk
}

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

// TestPool_CascadeFail_SingleLevel: A fails; B depends on A and is PENDING.
// cascadeFail must mark B CANCELLED with a message referencing A.
func TestPool_CascadeFail_SingleLevel(t *testing.T) {
	store := testStore(t)
	a := depTask("cf-a", nil, task.StateFailed)
	b := depTask("cf-b", []string{"cf-a"}, task.StatePending)
	if err := store.CreateTask(a); err != nil {
		t.Fatal(err)
	}
	if err := store.CreateTask(b); err != nil {
		t.Fatal(err)
	}

	pool := cascadeTestPool(t, store)
	pool.cascadeFail("cf-a", "build failed")

	got, err := store.GetTask("cf-b")
	if err != nil {
		t.Fatal(err)
	}
	if got.State != task.StateCancelled {
		t.Fatalf("cf-b state: want CANCELLED, got %s", got.State)
	}

	execs, err := store.ListExecutions("cf-b")
	if err != nil {
		t.Fatal(err)
	}
	if len(execs) != 1 {
		t.Fatalf("expected 1 execution recorded for cf-b, got %d", len(execs))
	}
	if execs[0].Status != "CANCELLED" {
		t.Errorf("execution status: want CANCELLED, got %q", execs[0].Status)
	}
	if !strings.Contains(execs[0].ErrorMsg, "cf-a") {
		t.Errorf("execution ErrorMsg should reference upstream task cf-a, got %q", execs[0].ErrorMsg)
	}
}

// TestPool_CascadeFail_MultiLevelRecursion: A fails, B depends on A, C
// depends on B. Both B and C must end up CANCELLED — cascadeFail must
// recurse through the whole subtree, not just cancel direct dependents.
func TestPool_CascadeFail_MultiLevelRecursion(t *testing.T) {
	store := testStore(t)
	a := depTask("cfm-a", nil, task.StateFailed)
	b := depTask("cfm-b", []string{"cfm-a"}, task.StatePending)
	c := depTask("cfm-c", []string{"cfm-b"}, task.StatePending)
	for _, tk := range []*task.Task{a, b, c} {
		if err := store.CreateTask(tk); err != nil {
			t.Fatal(err)
		}
	}

	pool := cascadeTestPool(t, store)
	pool.cascadeFail("cfm-a", "build failed")

	gotB, err := store.GetTask("cfm-b")
	if err != nil {
		t.Fatal(err)
	}
	gotC, err := store.GetTask("cfm-c")
	if err != nil {
		t.Fatal(err)
	}
	if gotB.State != task.StateCancelled {
		t.Errorf("cfm-b state: want CANCELLED, got %s", gotB.State)
	}
	if gotC.State != task.StateCancelled {
		t.Errorf("cfm-c state: want CANCELLED, got %s", gotC.State)
	}
}

// TestPool_CascadeFail_LeavesRunningAndCompletedAlone: dependents that are
// already RUNNING or already terminal (COMPLETED) when the cascade fires
// must be left untouched, not force-cancelled.
func TestPool_CascadeFail_LeavesRunningAndCompletedAlone(t *testing.T) {
	store := testStore(t)
	a := depTask("cfr-a", nil, task.StateFailed)
	running := depTask("cfr-running", []string{"cfr-a"}, task.StateRunning)
	completed := depTask("cfr-completed", []string{"cfr-a"}, task.StateCompleted)
	for _, tk := range []*task.Task{a, running, completed} {
		if err := store.CreateTask(tk); err != nil {
			t.Fatal(err)
		}
	}

	pool := cascadeTestPool(t, store)
	pool.cascadeFail("cfr-a", "build failed")

	gotRunning, err := store.GetTask("cfr-running")
	if err != nil {
		t.Fatal(err)
	}
	if gotRunning.State != task.StateRunning {
		t.Errorf("cfr-running state: want unchanged RUNNING, got %s", gotRunning.State)
	}

	gotCompleted, err := store.GetTask("cfr-completed")
	if err != nil {
		t.Fatal(err)
	}
	if gotCompleted.State != task.StateCompleted {
		t.Errorf("cfr-completed state: want unchanged COMPLETED, got %s", gotCompleted.State)
	}

	// No execution records should have been created for either — cascadeFail
	// should not have touched them at all.
	if execs, _ := store.ListExecutions("cfr-running"); len(execs) != 0 {
		t.Errorf("expected no executions recorded for cfr-running, got %d", len(execs))
	}
	if execs, _ := store.ListExecutions("cfr-completed"); len(execs) != 0 {
		t.Errorf("expected no executions recorded for cfr-completed, got %d", len(execs))
	}
}

// TestPool_CascadeFail_CycleGuard proves cascadeFail terminates on a
// dependency cycle instead of recursing forever. task.Validate and
// storage.CreateTask do not reject dependency cycles today (there is no
// cycle-detection anywhere in task creation), so this guard is load-bearing,
// not just defense-in-depth.
func TestPool_CascadeFail_CycleGuard(t *testing.T) {
	store := testStore(t)
	a := depTask("cyc-a", []string{"cyc-b"}, task.StatePending)
	b := depTask("cyc-b", []string{"cyc-a"}, task.StatePending)
	if err := store.CreateTask(a); err != nil {
		t.Fatal(err)
	}
	if err := store.CreateTask(b); err != nil {
		t.Fatal(err)
	}

	pool := cascadeTestPool(t, store)

	done := make(chan struct{})
	go func() {
		pool.cascadeFail("cyc-a", "boom")
		close(done)
	}()
	select {
	case <-done:
	case <-time.After(5 * time.Second):
		t.Fatal("cascadeFail did not terminate on a dependency cycle — infinite recursion?")
	}

	gotA, err := store.GetTask("cyc-a")
	if err != nil {
		t.Fatal(err)
	}
	gotB, err := store.GetTask("cyc-b")
	if err != nil {
		t.Fatal(err)
	}
	if gotA.State != task.StateCancelled {
		t.Errorf("cyc-a state: want CANCELLED, got %s", gotA.State)
	}
	if gotB.State != task.StateCancelled {
		t.Errorf("cyc-b state: want CANCELLED, got %s", gotB.State)
	}
}

// TestPool_CascadeFail_WiredIntoHandleRunResult verifies cascadeFail is
// actually invoked when a task's run terminates in a failure state via the
// normal handleRunResult path (not just when called directly), using a real
// store so ListDependents sees real data.
func TestPool_CascadeFail_WiredIntoHandleRunResult(t *testing.T) {
	store := testStore(t)
	a := depTask("hrr-cascade-a", nil, task.StateRunning)
	b := depTask("hrr-cascade-b", []string{"hrr-cascade-a"}, task.StatePending)
	if err := store.CreateTask(a); err != nil {
		t.Fatal(err)
	}
	if err := store.CreateTask(b); err != nil {
		t.Fatal(err)
	}

	pool := cascadeTestPool(t, store)
	execRec := &storage.Execution{ID: "hrr-cascade-exec", TaskID: a.ID, Status: "RUNNING"}
	pool.handleRunResult(context.Background(), a, execRec, errors.New("boom"), "claude")
	<-pool.resultCh

	gotB, err := store.GetTask("hrr-cascade-b")
	if err != nil {
		t.Fatal(err)
	}
	if gotB.State != task.StateCancelled {
		t.Errorf("hrr-cascade-b state: want CANCELLED after upstream FAILED, got %s", gotB.State)
	}
}