package api

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"visiona-backend/internal/session"
)

// fakeSessionStore 是測試用 Store 實作，只回 List 結果；其他方法 panic 表示
// 不應被呼叫（以利早期偵錯）。
type fakeSessionStore struct {
	sessions []*session.Summary
	listErr  error
}

func (f *fakeSessionStore) Register(context.Context, string, session.Handle) error {
	panic("Register should not be called")
}
func (f *fakeSessionStore) Unregister(context.Context, string) error {
	panic("Unregister should not be called")
}
func (f *fakeSessionStore) Lookup(context.Context, string) (session.Handle, error) {
	panic("Lookup should not be called")
}
func (f *fakeSessionStore) Exists(context.Context, string) (bool, error) {
	panic("Exists should not be called")
}
func (f *fakeSessionStore) List(context.Context) ([]*session.Summary, error) {
	return f.sessions, f.listErr
}
func (f *fakeSessionStore) Heartbeat(context.Context, string) error {
	panic("Heartbeat should not be called")
}
func (f *fakeSessionStore) CleanupExpired(context.Context, time.Duration) (int, error) {
	panic("CleanupExpired should not be called")
}

// fakePinger 是 /healthz 依賴 ping 的測試替身（純 Go，不需真 DB）。
type fakePinger struct{ err error }

func (f fakePinger) Ping(context.Context) error { return f.err }

// TestHealthzHandler 驗證 /healthz 在「無依賴」時回 200 + status:ok（退化為最小檢查）。
func TestHealthzHandler(t *testing.T) {
	r := gin.New()
	r.GET("/healthz", HealthzHandler(HealthDeps{}))

	w := httptest.NewRecorder()
	r.ServeHTTP(w, httptest.NewRequest(http.MethodGet, "/healthz", nil))
	assert.Equal(t, http.StatusOK, w.Code)
	assert.Contains(t, w.Body.String(), `"status":"ok"`)
}

// TestHealthz_AllDepsHealthy 驗證 PG + Redis 都 ping 成功 → 200 + checks 全 ok。
func TestHealthz_AllDepsHealthy(t *testing.T) {
	r := gin.New()
	r.GET("/healthz", HealthzHandler(HealthDeps{
		DBPool: fakePinger{},
		Redis:  fakePinger{},
	}))

	w := httptest.NewRecorder()
	r.ServeHTTP(w, httptest.NewRequest(http.MethodGet, "/healthz", nil))
	assert.Equal(t, http.StatusOK, w.Code)
	assert.Contains(t, w.Body.String(), `"postgres":"ok"`)
	assert.Contains(t, w.Body.String(), `"redis":"ok"`)
}

// TestHealthz_PostgresDown 驗證 PG ping 失敗 → 503（塊 5.4 fail-fast）。
func TestHealthz_PostgresDown(t *testing.T) {
	r := gin.New()
	r.GET("/healthz", HealthzHandler(HealthDeps{
		DBPool: fakePinger{err: errors.New("connection refused")},
	}))

	w := httptest.NewRecorder()
	r.ServeHTTP(w, httptest.NewRequest(http.MethodGet, "/healthz", nil))
	assert.Equal(t, http.StatusServiceUnavailable, w.Code)
	assert.Contains(t, w.Body.String(), `"postgres":"down"`)
	// 不洩漏 raw error 進 response（只進 log）
	assert.NotContains(t, w.Body.String(), "connection refused")
}

// TestHealthz_RedisDown 驗證 Redis 啟用但 ping 失敗 → 503；PG ok 仍標出 redis down。
func TestHealthz_RedisDown(t *testing.T) {
	r := gin.New()
	r.GET("/healthz", HealthzHandler(HealthDeps{
		DBPool: fakePinger{},
		Redis:  fakePinger{err: errors.New("redis down")},
	}))

	w := httptest.NewRecorder()
	r.ServeHTTP(w, httptest.NewRequest(http.MethodGet, "/healthz", nil))
	assert.Equal(t, http.StatusServiceUnavailable, w.Code)
	assert.Contains(t, w.Body.String(), `"redis":"down"`)
	assert.Contains(t, w.Body.String(), `"postgres":"ok"`)
}

// TestHealthz_RedisNotEnabled 驗證 Redis 未啟用（nil）→ 不檢查、PG ok 即 200。
func TestHealthz_RedisNotEnabled(t *testing.T) {
	r := gin.New()
	r.GET("/healthz", HealthzHandler(HealthDeps{
		DBPool: fakePinger{},
		// Redis nil — 未啟用，略過
	}))

	w := httptest.NewRecorder()
	r.ServeHTTP(w, httptest.NewRequest(http.MethodGet, "/healthz", nil))
	assert.Equal(t, http.StatusOK, w.Code)
	assert.NotContains(t, w.Body.String(), "redis")
}

// TestSystemHealth_TunnelDisconnected 驗證沒 session 時回 connected=false。
func TestSystemHealth_TunnelDisconnected(t *testing.T) {
	r := gin.New()
	r.Use(RequestIDMiddleware())
	g := r.Group("/api")
	registerSystemRoutes(g, Deps{
		SessionStore: &fakeSessionStore{sessions: nil},
		Logger:       nil,
	})

	w := httptest.NewRecorder()
	r.ServeHTTP(w, httptest.NewRequest(http.MethodGet, "/api/system/health", nil))
	require.Equal(t, http.StatusOK, w.Code)

	var body SuccessBody
	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &body))
	require.True(t, body.Success)
	data, _ := body.Data.(map[string]any)
	require.NotNil(t, data)
	assert.Equal(t, "ok", data["api_server"])
	assert.Equal(t, false, data["tunnel_connected"])
}

// TestSystemHealth_TunnelConnected 驗證有 session 時回 connected=true 並帶 last_seen_at。
func TestSystemHealth_TunnelConnected(t *testing.T) {
	now := time.Now().UTC().Truncate(time.Second)
	r := gin.New()
	r.Use(RequestIDMiddleware())
	g := r.Group("/api")
	registerSystemRoutes(g, Deps{
		SessionStore: &fakeSessionStore{
			sessions: []*session.Summary{
				{Token: "vAc_a", LastHeartbeat: now.Add(-5 * time.Second)},
				{Token: "vAc_b", LastHeartbeat: now}, // 最新
			},
		},
	})

	w := httptest.NewRecorder()
	r.ServeHTTP(w, httptest.NewRequest(http.MethodGet, "/api/system/health", nil))
	require.Equal(t, http.StatusOK, w.Code)

	var body SuccessBody
	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &body))
	data := body.Data.(map[string]any)
	assert.Equal(t, true, data["tunnel_connected"])
	assert.EqualValues(t, 2, data["agent_session_count"])
	assert.NotEmpty(t, data["agent_last_seen_at"])
}

// TestSystemInfo 驗證 GET /api/system/info 回基本欄位。
func TestSystemInfo(t *testing.T) {
	r := gin.New()
	r.Use(RequestIDMiddleware())
	g := r.Group("/api")
	registerSystemRoutes(g, Deps{})

	w := httptest.NewRecorder()
	r.ServeHTTP(w, httptest.NewRequest(http.MethodGet, "/api/system/info", nil))
	require.Equal(t, http.StatusOK, w.Code)

	var body SuccessBody
	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &body))
	data := body.Data.(map[string]any)
	assert.Equal(t, "visiona-api-server", data["service"])
	assert.Equal(t, "phase-0-prototype", data["phase"])
}