package api

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"testing"

	"github.com/sipeed/picoclaw/pkg/config"
	"github.com/sipeed/picoclaw/pkg/memory"
	"github.com/sipeed/picoclaw/pkg/providers"
	"github.com/sipeed/picoclaw/pkg/session"
)

func sessionsTestDir(t *testing.T, configPath string) string {
	t.Helper()

	cfg, err := config.LoadConfig(configPath)
	if err != nil {
		t.Fatalf("LoadConfig() error = %v", err)
	}

	dir := filepath.Join(cfg.Agents.Defaults.Workspace, "sessions")
	if err := os.MkdirAll(dir, 0o755); err != nil {
		t.Fatalf("MkdirAll() error = %v", err)
	}
	return dir
}

func TestHandleListSessions_JSONLStorage(t *testing.T) {
	configPath, cleanup := setupOAuthTestEnv(t)
	defer cleanup()

	dir := sessionsTestDir(t, configPath)
	store, err := memory.NewJSONLStore(dir)
	if err != nil {
		t.Fatalf("NewJSONLStore() error = %v", err)
	}

	sessionKey := picoSessionPrefix + "history-jsonl"
	if err := store.AddFullMessage(nil, sessionKey, providers.Message{
		Role:    "user",
		Content: "Explain why the history API is empty after migration.",
	}); err != nil {
		t.Fatalf("AddFullMessage(user) error = %v", err)
	}
	if err := store.AddFullMessage(nil, sessionKey, providers.Message{
		Role:    "assistant",
		Content: "Because the API still reads only legacy JSON session files.",
	}); err != nil {
		t.Fatalf("AddFullMessage(assistant) error = %v", err)
	}
	if err := store.AddFullMessage(nil, sessionKey, providers.Message{
		Role:    "tool",
		Content: "ignored",
	}); err != nil {
		t.Fatalf("AddFullMessage(tool) error = %v", err)
	}
	if err := store.SetSummary(nil, sessionKey, "JSONL-backed session"); err != nil {
		t.Fatalf("SetSummary() error = %v", err)
	}

	h := NewHandler(configPath)
	mux := http.NewServeMux()
	h.RegisterRoutes(mux)

	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/api/sessions", nil)
	mux.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want %d, body=%s", rec.Code, http.StatusOK, rec.Body.String())
	}

	var items []sessionListItem
	if err := json.Unmarshal(rec.Body.Bytes(), &items); err != nil {
		t.Fatalf("Unmarshal() error = %v", err)
	}
	if len(items) != 1 {
		t.Fatalf("len(items) = %d, want 1", len(items))
	}
	if items[0].ID != "history-jsonl" {
		t.Fatalf("items[0].ID = %q, want %q", items[0].ID, "history-jsonl")
	}
	if items[0].MessageCount != 2 {
		t.Fatalf("items[0].MessageCount = %d, want 2", items[0].MessageCount)
	}
	if items[0].Title != "JSONL-backed session" {
		t.Fatalf("items[0].Title = %q, want %q", items[0].Title, "JSONL-backed session")
	}
	if items[0].Preview != "Explain why the history API is empty after migration." {
		t.Fatalf("items[0].Preview = %q", items[0].Preview)
	}
}

func TestHandleListSessions_TitleUsesTrimmedSummary(t *testing.T) {
	configPath, cleanup := setupOAuthTestEnv(t)
	defer cleanup()

	dir := sessionsTestDir(t, configPath)
	store, err := memory.NewJSONLStore(dir)
	if err != nil {
		t.Fatalf("NewJSONLStore() error = %v", err)
	}

	sessionKey := picoSessionPrefix + "summary-title"
	if err := store.AddFullMessage(nil, sessionKey, providers.Message{
		Role:    "user",
		Content: "fallback preview",
	}); err != nil {
		t.Fatalf("AddFullMessage() error = %v", err)
	}
	if err := store.SetSummary(
		nil,
		sessionKey,
		"  This summary is intentionally longer than sixty characters so it must be truncated in the history menu.  ",
	); err != nil {
		t.Fatalf("SetSummary() error = %v", err)
	}

	h := NewHandler(configPath)
	mux := http.NewServeMux()
	h.RegisterRoutes(mux)

	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/api/sessions", nil)
	mux.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want %d, body=%s", rec.Code, http.StatusOK, rec.Body.String())
	}

	var items []sessionListItem
	if err := json.Unmarshal(rec.Body.Bytes(), &items); err != nil {
		t.Fatalf("Unmarshal() error = %v", err)
	}
	if len(items) != 1 {
		t.Fatalf("len(items) = %d, want 1", len(items))
	}
	expectedTitle := truncateRunes(
		"This summary is intentionally longer than sixty characters so it must be truncated in the history menu.",
		maxSessionTitleRunes,
	)
	if items[0].Title != expectedTitle {
		t.Fatalf("items[0].Title = %q", items[0].Title)
	}
	if items[0].Preview != "fallback preview" {
		t.Fatalf("items[0].Preview = %q, want %q", items[0].Preview, "fallback preview")
	}
}

func TestHandleGetSession_JSONLStorage(t *testing.T) {
	configPath, cleanup := setupOAuthTestEnv(t)
	defer cleanup()

	dir := sessionsTestDir(t, configPath)
	store, err := memory.NewJSONLStore(dir)
	if err != nil {
		t.Fatalf("NewJSONLStore() error = %v", err)
	}

	sessionKey := picoSessionPrefix + "detail-jsonl"
	for _, msg := range []providers.Message{
		{Role: "user", Content: "first"},
		{Role: "assistant", Content: "second"},
		{Role: "tool", Content: "ignored"},
	} {
		if err := store.AddFullMessage(nil, sessionKey, msg); err != nil {
			t.Fatalf("AddFullMessage() error = %v", err)
		}
	}
	if err := store.SetSummary(nil, sessionKey, "detail summary"); err != nil {
		t.Fatalf("SetSummary() error = %v", err)
	}

	h := NewHandler(configPath)
	mux := http.NewServeMux()
	h.RegisterRoutes(mux)

	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/api/sessions/detail-jsonl", nil)
	mux.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want %d, body=%s", rec.Code, http.StatusOK, rec.Body.String())
	}

	var resp struct {
		ID       string `json:"id"`
		Summary  string `json:"summary"`
		Messages []struct {
			Role    string `json:"role"`
			Content string `json:"content"`
		} `json:"messages"`
	}
	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
		t.Fatalf("Unmarshal() error = %v", err)
	}
	if resp.ID != "detail-jsonl" {
		t.Fatalf("resp.ID = %q, want %q", resp.ID, "detail-jsonl")
	}
	if resp.Summary != "detail summary" {
		t.Fatalf("resp.Summary = %q, want %q", resp.Summary, "detail summary")
	}
	if len(resp.Messages) != 2 {
		t.Fatalf("len(resp.Messages) = %d, want 2", len(resp.Messages))
	}
	if resp.Messages[0].Role != "user" || resp.Messages[0].Content != "first" {
		t.Fatalf("first message = %#v, want user/first", resp.Messages[0])
	}
	if resp.Messages[1].Role != "assistant" || resp.Messages[1].Content != "second" {
		t.Fatalf("second message = %#v, want assistant/second", resp.Messages[1])
	}
}

func TestHandleDeleteSession_JSONLStorage(t *testing.T) {
	configPath, cleanup := setupOAuthTestEnv(t)
	defer cleanup()

	dir := sessionsTestDir(t, configPath)
	store, err := memory.NewJSONLStore(dir)
	if err != nil {
		t.Fatalf("NewJSONLStore() error = %v", err)
	}

	sessionKey := picoSessionPrefix + "delete-jsonl"
	if err := store.AddFullMessage(nil, sessionKey, providers.Message{
		Role:    "user",
		Content: "delete me",
	}); err != nil {
		t.Fatalf("AddFullMessage() error = %v", err)
	}
	if err := store.SetSummary(nil, sessionKey, "delete summary"); err != nil {
		t.Fatalf("SetSummary() error = %v", err)
	}

	h := NewHandler(configPath)
	mux := http.NewServeMux()
	h.RegisterRoutes(mux)

	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodDelete, "/api/sessions/delete-jsonl", nil)
	mux.ServeHTTP(rec, req)

	if rec.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want %d, body=%s", rec.Code, http.StatusNoContent, rec.Body.String())
	}

	base := filepath.Join(dir, sanitizeSessionKey(sessionKey))
	for _, path := range []string{base + ".jsonl", base + ".meta.json"} {
		if _, err := os.Stat(path); !os.IsNotExist(err) {
			t.Fatalf("expected %s to be removed, stat err = %v", path, err)
		}
	}
}

func TestHandleGetSession_LegacyJSONFallback(t *testing.T) {
	configPath, cleanup := setupOAuthTestEnv(t)
	defer cleanup()

	dir := sessionsTestDir(t, configPath)
	manager := session.NewSessionManager(dir)
	sessionKey := picoSessionPrefix + "legacy-json"
	manager.AddMessage(sessionKey, "user", "legacy user")
	manager.AddMessage(sessionKey, "assistant", "legacy assistant")
	if err := manager.Save(sessionKey); err != nil {
		t.Fatalf("Save() error = %v", err)
	}

	h := NewHandler(configPath)
	mux := http.NewServeMux()
	h.RegisterRoutes(mux)

	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/api/sessions/legacy-json", nil)
	mux.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want %d, body=%s", rec.Code, http.StatusOK, rec.Body.String())
	}
}

func TestHandleSessions_FiltersEmptyJSONLFiles(t *testing.T) {
	configPath, cleanup := setupOAuthTestEnv(t)
	defer cleanup()

	dir := sessionsTestDir(t, configPath)
	base := filepath.Join(dir, sanitizeSessionKey(picoSessionPrefix+"empty-jsonl"))
	if err := os.WriteFile(base+".jsonl", []byte{}, 0o644); err != nil {
		t.Fatalf("WriteFile(jsonl) error = %v", err)
	}

	h := NewHandler(configPath)
	mux := http.NewServeMux()
	h.RegisterRoutes(mux)

	listRec := httptest.NewRecorder()
	listReq := httptest.NewRequest(http.MethodGet, "/api/sessions", nil)
	mux.ServeHTTP(listRec, listReq)

	if listRec.Code != http.StatusOK {
		t.Fatalf("list status = %d, want %d, body=%s", listRec.Code, http.StatusOK, listRec.Body.String())
	}

	var items []sessionListItem
	if err := json.Unmarshal(listRec.Body.Bytes(), &items); err != nil {
		t.Fatalf("Unmarshal(list) error = %v", err)
	}
	if len(items) != 0 {
		t.Fatalf("len(items) = %d, want 0", len(items))
	}

	detailRec := httptest.NewRecorder()
	detailReq := httptest.NewRequest(http.MethodGet, "/api/sessions/empty-jsonl", nil)
	mux.ServeHTTP(detailRec, detailReq)

	if detailRec.Code != http.StatusNotFound {
		t.Fatalf("detail status = %d, want %d, body=%s", detailRec.Code, http.StatusNotFound, detailRec.Body.String())
	}
}