package executor

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"sync/atomic"
	"testing"

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

func writeStreamLog(t *testing.T, lines []string) string {
	t.Helper()
	dir := t.TempDir()
	path := filepath.Join(dir, "stdout.log")
	var sb strings.Builder
	for _, l := range lines {
		sb.WriteString(l)
		sb.WriteString("\n")
	}
	if err := os.WriteFile(path, []byte(sb.String()), 0600); err != nil {
		t.Fatal(err)
	}
	return path
}

func TestSynthesizeSummary_NilClient(t *testing.T) {
	got := synthesizeSummary(context.Background(), nil, "/some/path")
	if got != "" {
		t.Errorf("nil client: want empty, got %q", got)
	}
}

func TestSynthesizeSummary_EmptyPath(t *testing.T) {
	c := &llm.Client{Endpoint: "http://unused", Model: "x"}
	got := synthesizeSummary(context.Background(), c, "")
	if got != "" {
		t.Errorf("empty path: want empty, got %q", got)
	}
}

func TestSynthesizeSummary_MissingFile(t *testing.T) {
	c := &llm.Client{Endpoint: "http://unused", Model: "x"}
	got := synthesizeSummary(context.Background(), c, "/nonexistent/file.log")
	if got != "" {
		t.Errorf("missing file: want empty, got %q", got)
	}
}

func TestSynthesizeSummary_EmptyAssistantContent(t *testing.T) {
	// Log contains only system/result events — no assistant text. The function
	// should short-circuit without calling the LLM.
	path := writeStreamLog(t, []string{
		`{"type":"system","subtype":"init"}`,
		`{"type":"result","subtype":"success","total_cost_usd":0}`,
	})

	var calls int32
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		atomic.AddInt32(&calls, 1)
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprintln(w, `{"choices":[{"message":{"content":"should not be returned"},"finish_reason":"stop"}],"usage":{}}`)
	}))
	defer srv.Close()
	c := &llm.Client{Endpoint: srv.URL + "/v1", Model: "x"}

	got := synthesizeSummary(context.Background(), c, path)
	if got != "" {
		t.Errorf("empty content: want empty, got %q", got)
	}
	if atomic.LoadInt32(&calls) != 0 {
		t.Errorf("LLM should not be called for empty assistant content")
	}
}

func TestSynthesizeSummary_LLMSuccess(t *testing.T) {
	path := writeStreamLog(t, []string{
		`{"type":"assistant","message":{"content":[{"type":"text","text":"Ran the tests."}]}}`,
		`{"type":"assistant","message":{"content":[{"type":"text","text":"Fixed the import."}]}}`,
		`{"type":"result","subtype":"success"}`,
	})

	var capturedUser string
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var body struct {
			Messages []struct {
				Role, Content string
			} `json:"messages"`
		}
		json.NewDecoder(r.Body).Decode(&body)
		for _, m := range body.Messages {
			if m.Role == "user" {
				capturedUser = m.Content
			}
		}
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprintln(w, `{"choices":[{"message":{"content":"  Agent ran tests and fixed an import.  "},"finish_reason":"stop"}],"usage":{}}`)
	}))
	defer srv.Close()
	c := &llm.Client{Endpoint: srv.URL + "/v1", Model: "x"}

	got := synthesizeSummary(context.Background(), c, path)
	if got != "Agent ran tests and fixed an import." {
		t.Errorf("summary: got %q", got)
	}
	if !strings.Contains(capturedUser, "Ran the tests.") {
		t.Errorf("user prompt missing first assistant text; got: %s", capturedUser)
	}
	if !strings.Contains(capturedUser, "Fixed the import.") {
		t.Errorf("user prompt missing second assistant text; got: %s", capturedUser)
	}
}

// TestPool_HandleRunResult_LLMSummaryFallback verifies the Pool falls back to
// LLM-synthesized summary when extractSummary returns empty.
func TestPool_HandleRunResult_LLMSummaryFallback(t *testing.T) {
	// stdout has assistant text but no "## Summary" heading.
	stdoutPath := writeStreamLog(t, []string{
		`{"type":"assistant","message":{"content":[{"type":"text","text":"Did the work without writing a summary section."}]}}`,
	})

	llmSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprintln(w, `{"choices":[{"message":{"content":"Synthesized summary."},"finish_reason":"stop"}],"usage":{}}`)
	}))
	defer llmSrv.Close()

	store := newMinimalMockStore()
	pool := newPoolWithMockStore(store)
	pool.LLM = &llm.Client{Endpoint: llmSrv.URL + "/v1", Model: "x"}

	tk := makeTask("synth-summary")
	store.tasks[tk.ID] = tk
	exec := &storage.Execution{ID: "e-synth", TaskID: tk.ID, Status: "RUNNING", StdoutPath: stdoutPath}

	pool.handleRunResult(context.Background(), tk, exec, nil, "claude")

	id, summary, ok := store.lastSummaryUpdate()
	if !ok {
		t.Fatalf("expected UpdateTaskSummary to be called")
	}
	if id != tk.ID {
		t.Errorf("summary recorded for wrong task: %q", id)
	}
	if summary != "Synthesized summary." {
		t.Errorf("summary: got %q", summary)
	}

	// Drain the result channel so the test exits cleanly.
	<-pool.resultCh
}

// TestPool_HandleRunResult_ExtractSummaryWins verifies the LLM is NOT called
// when the agent already wrote a "## Summary" section.
func TestPool_HandleRunResult_ExtractSummaryWins(t *testing.T) {
	stdoutPath := writeStreamLog(t, []string{
		`{"type":"assistant","message":{"content":[{"type":"text","text":"## Summary\nAgent wrote its own summary."}]}}`,
	})

	var llmCalls int32
	llmSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		atomic.AddInt32(&llmCalls, 1)
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprintln(w, `{"choices":[{"message":{"content":"should not be used"},"finish_reason":"stop"}],"usage":{}}`)
	}))
	defer llmSrv.Close()

	store := newMinimalMockStore()
	pool := newPoolWithMockStore(store)
	pool.LLM = &llm.Client{Endpoint: llmSrv.URL + "/v1", Model: "x"}

	tk := makeTask("agent-summary")
	store.tasks[tk.ID] = tk
	exec := &storage.Execution{ID: "e-agent", TaskID: tk.ID, Status: "RUNNING", StdoutPath: stdoutPath}

	pool.handleRunResult(context.Background(), tk, exec, nil, "claude")

	if got := atomic.LoadInt32(&llmCalls); got != 0 {
		t.Errorf("LLM should not be called when ## Summary is present; got %d calls", got)
	}
	_, summary, ok := store.lastSummaryUpdate()
	if !ok {
		t.Fatalf("expected UpdateTaskSummary")
	}
	if summary != "Agent wrote its own summary." {
		t.Errorf("summary: got %q (want extractSummary output)", summary)
	}
	<-pool.resultCh
}

func TestSynthesizeSummary_LLMFailure_ReturnsEmpty(t *testing.T) {
	path := writeStreamLog(t, []string{
		`{"type":"assistant","message":{"content":[{"type":"text","text":"Did something."}]}}`,
	})
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		http.Error(w, "boom", http.StatusInternalServerError)
	}))
	defer srv.Close()
	c := &llm.Client{Endpoint: srv.URL + "/v1", Model: "x"}

	got := synthesizeSummary(context.Background(), c, path)
	if got != "" {
		t.Errorf("LLM failure: want empty, got %q", got)
	}
}

// TestReadAssistantTextTail_TailingLargeFile verifies the seek-to-tail
// behavior drops early content but keeps later assistant text.
func TestReadAssistantTextTail_TailingLargeFile(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "stdout.log")
	f, err := os.Create(path)
	if err != nil {
		t.Fatal(err)
	}
	// Write a ton of garbage assistant lines, then a final marker.
	for i := 0; i < 500; i++ {
		fmt.Fprintf(f, `{"type":"assistant","message":{"content":[{"type":"text","text":"filler line that should be in the early part of a large file %04d"}]}}`+"\n", i)
	}
	fmt.Fprintln(f, `{"type":"assistant","message":{"content":[{"type":"text","text":"FINAL_MARKER_LINE"}]}}`)
	f.Close()

	got := readAssistantTextTail(path, 4*1024) // 4 KB cap
	if !strings.Contains(got, "FINAL_MARKER_LINE") {
		t.Errorf("tail should contain final line; got: %s", got)
	}
	if strings.Contains(got, "filler line that should be in the early part of a large file 0000") {
		end := 200
		if len(got) < end {
			end = len(got)
		}
		t.Errorf("tail should NOT contain very-early line; got first 200 chars: %s", got[:end])
	}
}