package httpx

import (
	"net/http"

	"github.com/go-chi/chi/v5"
	"log/slog"

	"github.com/yan1h/agent-coding-workflow/internal/transport/http/middleware"
)

// RouterDeps bundles the dependencies needed to assemble the router.
// MVP exposes only liveness/readiness probe hooks; later phases (auth
// resolver, module handlers, etc.) will add fields here rather than
// growing NewRouter's signature.
type RouterDeps struct {
	// HealthCheck is invoked from GET /healthz. Returning a non-nil
	// error renders 503 with the error message as the body. If nil,
	// /healthz unconditionally returns 200 "ok".
	HealthCheck func(*http.Request) error
	// ReadyCheck is invoked from GET /readyz with the same contract.
	ReadyCheck func(*http.Request) error
	// SPAHandler 为 nil 时禁用前端 fallback；非 nil 时挂到 chi NotFound，
	// 把未匹配的请求交给 SPA handler 处理（静态文件 + index.html 回退）。
	SPAHandler http.Handler
	// Logger 用于 Recover 和 Logger 中间件。为 nil 时跳过日志相关中间件。
	Logger *slog.Logger
}

// NewRouter builds the application's chi.Router with the standard
// liveness/readiness endpoints attached. The return type is the
// chi.Router interface (not *chi.Mux) so call sites depend only on
// behaviour shared with future routing layers.
func NewRouter(deps RouterDeps) chi.Router {
	r := chi.NewRouter()

	// 所有中间件必须在注册路由之前添加（chi 的强制要求）。
	r.Use(middleware.RequestID)
	if deps.Logger != nil {
		r.Use(middleware.Recover(deps.Logger))
		r.Use(middleware.Logger(deps.Logger))
	}

	r.Get("/healthz", func(w http.ResponseWriter, req *http.Request) {
		if deps.HealthCheck != nil {
			if err := deps.HealthCheck(req); err != nil {
				http.Error(w, err.Error(), http.StatusServiceUnavailable)
				return
			}
		}
		_, _ = w.Write([]byte("ok"))
	})

	r.Get("/readyz", func(w http.ResponseWriter, req *http.Request) {
		if deps.ReadyCheck != nil {
			if err := deps.ReadyCheck(req); err != nil {
				http.Error(w, err.Error(), http.StatusServiceUnavailable)
				return
			}
		}
		_, _ = w.Write([]byte("ok"))
	})

	if deps.SPAHandler != nil {
		r.NotFound(deps.SPAHandler.ServeHTTP)
	}

	return r
}