// Package notify 内的 handler.go 是通知 inbox 的 HTTP 接入层。它把已经
// 鉴权完成的请求路由到 Repository 的对应方法，并按统一的 response.go
// 风格（Google API 风格错误体）返回。
//
// 端点（统一前缀 /api/v1/notifications，全部需要登录）：
//
//	GET    /                  → 列表，参数 ?unread=true&limit=N
//	GET    /unread-count      → 未读计数
//	PATCH  /read-all          → 全部标已读
//	PATCH  /{id}/read         → 单条标已读
package notify

import (
	"net/http"
	"strconv"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/google/uuid"

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

// Handler 暴露 notify 模块的 HTTP 接口；依赖 Repository 与 SessionResolver。
// 不直接持有 Dispatcher——发送通知由其它模块通过 Dispatcher 完成，handler
// 仅服务 inbox 读取与状态变更。
type Handler struct {
	repo     Repository
	resolver middleware.SessionResolver
}

// NewHandler 构造 notify 模块的 HTTP handler。
func NewHandler(repo Repository, resolver middleware.SessionResolver) *Handler {
	return &Handler{repo: repo, resolver: resolver}
}

// Mount 把 inbox 路由挂到给定 chi.Router 上。Auth 中间件在子路由内统一注入。
func (h *Handler) Mount(r chi.Router) {
	r.Route("/api/v1/notifications", func(r chi.Router) {
		r.Use(middleware.Auth(h.resolver, middleware.AuthOptions{}))
		r.Get("/", h.list)
		r.Get("/unread-count", h.unreadCount)
		r.Patch("/read-all", h.readAll)
		r.Patch("/{id}/read", h.markRead)
	})
}

// notificationDTO 是 inbox 单条通知的对外 JSON 形态。created_at/read_at
// 统一序列化为 RFC3339 字符串；read_at 为 nil 时省略（omitempty）。
type notificationDTO struct {
	ID        string         `json:"id"`
	Topic     string         `json:"topic"`
	Severity  string         `json:"severity"`
	Title     string         `json:"title"`
	Body      string         `json:"body"`
	Link      string         `json:"link,omitempty"`
	Metadata  map[string]any `json:"metadata,omitempty"`
	ReadAt    *string        `json:"read_at,omitempty"`
	CreatedAt string         `json:"created_at"`
}

func (h *Handler) list(w http.ResponseWriter, r *http.Request) {
	uid, ok := middleware.UserIDFromContext(r.Context())
	if !ok {
		httpx.WriteError(w, middleware.RequestIDFromContext(r.Context()),
			errs.New(errs.CodeUnauthorized, "未认证"))
		return
	}
	unread := r.URL.Query().Get("unread") == "true"
	limit := 50
	if v := r.URL.Query().Get("limit"); v != "" {
		if n, err := strconv.Atoi(v); err == nil && n > 0 && n <= 200 {
			limit = n
		}
	}
	msgs, err := h.repo.List(r.Context(), uid, unread, limit)
	if err != nil {
		httpx.WriteError(w, middleware.RequestIDFromContext(r.Context()), err)
		return
	}
	out := make([]notificationDTO, 0, len(msgs))
	for _, m := range msgs {
		dto := notificationDTO{
			ID:        m.ID.String(),
			Topic:     m.Topic,
			Severity:  string(m.Severity),
			Title:     m.Title,
			Body:      m.Body,
			Link:      m.Link,
			Metadata:  m.Metadata,
			CreatedAt: m.CreatedAt.UTC().Format(time.RFC3339),
		}
		if m.ReadAt != nil {
			s := m.ReadAt.UTC().Format(time.RFC3339)
			dto.ReadAt = &s
		}
		out = append(out, dto)
	}
	httpx.WriteJSON(w, http.StatusOK, map[string]any{"items": out})
}

func (h *Handler) unreadCount(w http.ResponseWriter, r *http.Request) {
	uid, ok := middleware.UserIDFromContext(r.Context())
	if !ok {
		httpx.WriteError(w, middleware.RequestIDFromContext(r.Context()),
			errs.New(errs.CodeUnauthorized, "未认证"))
		return
	}
	n, err := h.repo.CountUnread(r.Context(), uid)
	if err != nil {
		httpx.WriteError(w, middleware.RequestIDFromContext(r.Context()), err)
		return
	}
	httpx.WriteJSON(w, http.StatusOK, map[string]any{"count": n})
}

func (h *Handler) markRead(w http.ResponseWriter, r *http.Request) {
	uid, ok := middleware.UserIDFromContext(r.Context())
	if !ok {
		httpx.WriteError(w, middleware.RequestIDFromContext(r.Context()),
			errs.New(errs.CodeUnauthorized, "未认证"))
		return
	}
	id, err := uuid.Parse(chi.URLParam(r, "id"))
	if err != nil {
		httpx.WriteError(w, middleware.RequestIDFromContext(r.Context()),
			errs.New(errs.CodeInvalidInput, "id 格式错误"))
		return
	}
	if err := h.repo.MarkRead(r.Context(), uid, id); err != nil {
		httpx.WriteError(w, middleware.RequestIDFromContext(r.Context()), err)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (h *Handler) readAll(w http.ResponseWriter, r *http.Request) {
	uid, ok := middleware.UserIDFromContext(r.Context())
	if !ok {
		httpx.WriteError(w, middleware.RequestIDFromContext(r.Context()),
			errs.New(errs.CodeUnauthorized, "未认证"))
		return
	}
	if err := h.repo.MarkAllRead(r.Context(), uid); err != nil {
		httpx.WriteError(w, middleware.RequestIDFromContext(r.Context()), err)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}