package api

import (
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"visiona-local/server/internal/api/handlers"
	"visiona-local/server/internal/api/ws"
	"visiona-local/server/internal/camera"
	"visiona-local/server/internal/device"
	"visiona-local/server/internal/flash"
	"visiona-local/server/internal/inference"
	"visiona-local/server/internal/model"
	"visiona-local/server/pkg/logger"

	"github.com/gin-gonic/gin"
)

func NewRouter(
	modelRepo *model.Repository,
	modelStore *model.ModelStore,
	deviceMgr *device.Manager,
	cameraMgr *camera.Manager,
	flashSvc *flash.Service,
	inferenceSvc *inference.Service,
	wsHub *ws.Hub,
	staticFS http.FileSystem,
	logBroadcaster *logger.Broadcaster,
	systemHandler *handlers.SystemHandler,
) *gin.Engine {
	// Use gin.New() instead of gin.Default() to replace the default logger
	// with one that also pushes to the WebSocket broadcaster.
	r := gin.New()
	r.Use(gin.Recovery())
	// M8-4：跳過高頻輪詢 endpoint 的 access log（TDD v2/server-lifecycle.md §9.1a）。
	// 瀏覽器每 10s poll 一次 boot-id；business code 也會定期輪詢 health，
	// 若每次都寫 access log 會把 business log 淹沒。
	//
	// 注意：broadcasterLogger 是我們自製的 middleware，不會直接套用 gin.LoggerConfig，
	// 因此 skip 邏輯在 broadcasterLogger 內部手動實作（見下方）。
	r.Use(broadcasterLogger(logBroadcaster))
	r.Use(CORSMiddleware())

	modelHandler := handlers.NewModelHandler(modelRepo)
	modelUploadHandler := handlers.NewModelUploadHandler(modelRepo, modelStore)
	deviceHandler := handlers.NewDeviceHandler(deviceMgr, flashSvc, inferenceSvc, wsHub)
	cameraHandler := handlers.NewCameraHandler(cameraMgr, deviceMgr, inferenceSvc, wsHub)

	api := r.Group("/api")
	{
		// System
		api.GET("/system/health", systemHandler.HealthCheck)
		api.GET("/system/info", systemHandler.Info)
		api.GET("/system/metrics", systemHandler.Metrics)
		api.GET("/system/deps", systemHandler.Deps)
		api.GET("/system/boot-id", systemHandler.BootID) // M8-4：瀏覽器 tab 用於偵測 server 重啟
		api.POST("/system/restart", systemHandler.Restart)
		api.POST("/system/install-driver", systemHandler.InstallDriver)
		// MAJ-4 補丁：Wails shutdown / Restart 前廣播 server:shutdown-imminent
		// 到 /ws/system，讓瀏覽器 tab 立即顯示 Offline Overlay。
		api.POST("/system/shutdown-notify", systemHandler.ShutdownNotify)

		// Models
		api.GET("/models", modelHandler.ListModels)
		api.GET("/models/:id", modelHandler.GetModel)
		api.POST("/models/upload", modelUploadHandler.UploadModel)
		api.DELETE("/models/:id", modelUploadHandler.DeleteModel)

		// Devices
		api.GET("/devices", deviceHandler.ListDevices)
		api.POST("/devices/scan", deviceHandler.ScanDevices)
		api.GET("/devices/:id", deviceHandler.GetDevice)
		api.POST("/devices/:id/connect", deviceHandler.ConnectDevice)
		api.POST("/devices/:id/disconnect", deviceHandler.DisconnectDevice)
		api.POST("/devices/:id/flash", deviceHandler.FlashDevice)
		api.POST("/devices/:id/inference/start", deviceHandler.StartInference)
		api.POST("/devices/:id/inference/stop", deviceHandler.StopInference)

		// Camera
		api.GET("/camera/list", cameraHandler.ListCameras)
		api.POST("/camera/start", cameraHandler.StartPipeline)
		api.POST("/camera/stop", cameraHandler.StopPipeline)
		api.GET("/camera/stream", cameraHandler.StreamMJPEG)

		// Media
		api.POST("/media/upload/image", cameraHandler.UploadImage)
		api.POST("/media/upload/video", cameraHandler.UploadVideo)
		api.POST("/media/upload/batch-images", cameraHandler.UploadBatchImages)
		api.GET("/media/batch-images/:index", cameraHandler.GetBatchImageFrame)
		api.POST("/media/seek", cameraHandler.SeekVideo)
	}

	// WebSocket
	r.GET("/ws/devices/events", ws.DeviceEventsHandler(wsHub, deviceMgr))
	r.GET("/ws/devices/:id/flash-progress", ws.FlashProgressHandler(wsHub))
	r.GET("/ws/devices/:id/inference", ws.InferenceHandler(wsHub, inferenceSvc))
	r.GET("/ws/server-logs", ws.ServerLogsHandler(wsHub, logBroadcaster))
	// MAJ-4 補丁：/ws/system — server:shutdown-imminent 事件訂閱
	r.GET("/ws/system", ws.SystemEventsHandler(wsHub))

	// Embedded frontend static file serving (production mode)
	if staticFS != nil {
		fileServer := http.FileServer(staticFS)

		// Serve Next.js-style static assets
		r.GET("/_next/*filepath", func(c *gin.Context) {
			fileServer.ServeHTTP(c.Writer, c.Request)
		})
		r.GET("/favicon.ico", func(c *gin.Context) {
			fileServer.ServeHTTP(c.Writer, c.Request)
		})

		// SPA fallback for all other routes (client-side routing)
		r.NoRoute(spaFallback(staticFS))
	}

	return r
}

// broadcasterLoggerSkipPaths 列出不寫 access log 的 endpoint（M8-4 TDD §9.1a）。
// 這些 endpoint 被瀏覽器或業務 code 高頻輪詢，每次都寫 log 會把 log 噴滿。
var broadcasterLoggerSkipPaths = map[string]struct{}{
	"/api/system/boot-id": {},
	"/api/system/health":  {},
}

// broadcasterLogger is a Gin middleware that logs HTTP requests to both
// stdout (like gin.Logger) and the WebSocket log broadcaster so that
// request logs are visible in the frontend Settings page.
//
// M8-4：對 broadcasterLoggerSkipPaths 裡列出的 endpoint 不寫 log，
// 避免把 access log 淹沒（瀏覽器每 10s poll boot-id，health 被業務 code 高頻輪詢）。
func broadcasterLogger(b *logger.Broadcaster) gin.HandlerFunc {
	return func(c *gin.Context) {
		start := time.Now()
		path := c.Request.URL.Path
		raw := c.Request.URL.RawQuery

		c.Next()

		// M8-4：跳過高頻輪詢 endpoint（比對只看 path，不含 query）
		if _, skip := broadcasterLoggerSkipPaths[path]; skip {
			return
		}

		latency := time.Since(start)
		status := c.Writer.Status()
		method := c.Request.Method

		if raw != "" {
			path = path + "?" + raw
		}

		msg := fmt.Sprintf("%3d | %13v | %-7s %s",
			status, latency, method, path)

		// Write to stdout (original Gin behaviour)
		fmt.Printf("[GIN] %s\n", msg)

		// Push to broadcaster for WebSocket streaming
		if b != nil {
			level := "INFO"
			if status >= 500 {
				level = "ERROR"
			} else if status >= 400 {
				level = "WARN"
			}
			b.Push(level, fmt.Sprintf("[GIN] %s", msg))
		}
	}
}

// spaFallback tries to serve the exact file from the embedded FS.
// If the file doesn't exist, it finds the best matching route shell HTML
// for Next.js static export client-side routing.
//
// Next.js static export with generateStaticParams creates:
//   /models/index.html       — static page
//   /models/_/index.html     — dynamic route shell (placeholder param '_')
//
// For a request like /models/yolov5-face-detection:
//  1. Try exact file → not found
//  2. Try /models/_/index.html → found → serve it (Next.js CSR picks up real param from URL)
//  3. Fall back to /index.html (root)
func spaFallback(staticFS http.FileSystem) gin.HandlerFunc {
	return func(c *gin.Context) {
		path := c.Request.URL.Path

		// Don't serve index.html for API or WebSocket routes
		if strings.HasPrefix(path, "/api/") || strings.HasPrefix(path, "/ws/") {
			c.Status(http.StatusNotFound)
			return
		}

		// Try to serve the exact file
		if f, err := staticFS.Open(path); err == nil {
			f.Close()
			http.FileServer(staticFS).ServeHTTP(c.Writer, c.Request)
			return
		}

		// Try Next.js dynamic route shell: replace last path segment with '_'
		// e.g. /models/yolov5 → /models/_/index.html
		//      /devices/kl520-0 → /devices/_/index.html
		//      /workspace/kl520-0 → /workspace/_/index.html
		segments := strings.Split(strings.TrimRight(path, "/"), "/")
		if len(segments) >= 2 {
			segments[len(segments)-1] = "_"
			shellPath := strings.Join(segments, "/") + "/index.html"
			if f, err := staticFS.Open(shellPath); err == nil {
				defer f.Close()
				c.Header("Content-Type", "text/html; charset=utf-8")
				c.Status(http.StatusOK)
				_, _ = io.Copy(c.Writer, f)
				return
			}
		}

		// Final fallback: root index.html
		index, err := staticFS.Open("/index.html")
		if err != nil {
			c.Status(http.StatusInternalServerError)
			return
		}
		defer index.Close()

		c.Header("Content-Type", "text/html; charset=utf-8")
		c.Status(http.StatusOK)
		_, _ = io.Copy(c.Writer, index)
	}
}