package middleware

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

	"mirror-proxy/internal/admin"
)

// CORS 跨域中间件
func CORS(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Access-Control-Allow-Origin", "*")
		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS, HEAD, PATCH")
		w.Header().Set("Access-Control-Allow-Headers", "Authorization, Content-Type, Accept, Origin, X-Requested-With")
		w.Header().Set("Access-Control-Expose-Headers", "Content-Length, Content-Type, X-Docker-Token")
		w.Header().Set("Access-Control-Max-Age", "86400")

		if r.Method == "OPTIONS" {
			w.WriteHeader(http.StatusOK)
			return
		}

		next.ServeHTTP(w, r)
	})
}

// Logger 日志中间件
func Logger(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		wrapped := &responseWriter{ResponseWriter: w, statusCode: http.StatusOK}
		next.ServeHTTP(wrapped, r)
		// 简单日志输出
		_ = start
	})
}

type responseWriter struct {
	http.ResponseWriter
	statusCode int
}

func (rw *responseWriter) WriteHeader(code int) {
	rw.statusCode = code
	rw.ResponseWriter.WriteHeader(code)
}

// SessionAuth 基于 Cookie Session 的认证中间件
func SessionAuth(sessions *admin.SessionStore, loginPath string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			cookie, err := r.Cookie("session")
			if err != nil {
				unauthorized(w, r, loginPath)
				return
			}

			_, ok := sessions.Get(cookie.Value)
			if !ok {
				unauthorized(w, r, loginPath)
				return
			}

			next.ServeHTTP(w, r)
		})
	}
}

func unauthorized(w http.ResponseWriter, r *http.Request, loginPath string) {
	accept := r.Header.Get("Accept")
	isAPI := strings.Contains(r.URL.Path, "/api/") ||
		strings.Contains(accept, "application/json")

	if isAPI {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusUnauthorized)
		w.Write([]byte(`{"error":"unauthorized"}`))
		return
	}

	http.Redirect(w, r, loginPath, http.StatusFound)
}

// StripPrefix 安全地移除路径前缀
func StripPrefix(prefix string, h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		p := strings.TrimPrefix(r.URL.Path, prefix)
		if p == r.URL.Path {
			http.NotFound(w, r)
			return
		}
		r.URL.Path = p
		h.ServeHTTP(w, r)
	})
}