package handler

import (
	"encoding/json"
	"errors"
	"net/http"
	"strings"

	"5803025015/w04/internal/middleware"
	"5803025015/w04/internal/models"
	"5803025015/w04/internal/store"

	"github.com/google/uuid"
)

type SnippetHandler struct {
	snippetStore SnippetStore
}

func NewSnippetHandler(snippetStore SnippetStore) *SnippetHandler {
	return &SnippetHandler{snippetStore: snippetStore}
}

type snippetRequest struct {
	Title   string `json:"title"`
	Content string `json:"content"`
}

type snippetResponse struct {
	ID      string `json:"id"`
	Title   string `json:"title"`
	Content string `json:"content"`
}

func toSnippetResponse(s *models.Snippet) snippetResponse {
	return snippetResponse{ID: s.ID, Title: s.Title, Content: s.Content}
}

func (h *SnippetHandler) Snippets(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		h.List(w, r)
	case http.MethodPost:
		h.Create(w, r)
	default:
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
	}
}

func (h *SnippetHandler) SnippetByID(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		h.Get(w, r)
	case http.MethodDelete:
		h.Delete(w, r)
	default:
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
	}
}

func (h *SnippetHandler) Create(w http.ResponseWriter, r *http.Request) {
	userID := middleware.GetUserID(r.Context())
	if userID == "" {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	var req snippetRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	req.Title = strings.TrimSpace(req.Title)
	req.Content = strings.TrimSpace(req.Content)
	if req.Title == "" || req.Content == "" {
		writeError(w, http.StatusBadRequest, "title and content are required")
		return
	}

	snippet := &models.Snippet{
		ID:      uuid.New().String(),
		Title:   req.Title,
		Content: req.Content,
		UserID:  userID,
	}

	if err := h.snippetStore.Create(r.Context(), snippet); err != nil {
		writeError(w, http.StatusInternalServerError, "internal error")
		return
	}

	writeJSON(w, http.StatusCreated, toSnippetResponse(snippet))
}

func (h *SnippetHandler) List(w http.ResponseWriter, r *http.Request) {
	userID := middleware.GetUserID(r.Context())
	if userID == "" {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	snippets, err := h.snippetStore.ListByOwner(r.Context(), userID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal error")
		return
	}

	out := make([]snippetResponse, 0, len(snippets))
	for _, s := range snippets {
		out = append(out, toSnippetResponse(s))
	}

	writeJSON(w, http.StatusOK, out)
}

func (h *SnippetHandler) Get(w http.ResponseWriter, r *http.Request) {
	id := extractID(r)
	if id == "" {
		writeError(w, http.StatusBadRequest, "missing id")
		return
	}

	snippet, err := h.snippetStore.GetByID(r.Context(), id)
	if err != nil {
		if errors.Is(err, store.ErrNotFound) {
			writeError(w, http.StatusNotFound, "snippet not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "internal error")
		return
	}

	writeJSON(w, http.StatusOK, toSnippetResponse(snippet))
}

func (h *SnippetHandler) Delete(w http.ResponseWriter, r *http.Request) {
	userID := middleware.GetUserID(r.Context())
	if userID == "" {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	id := extractID(r)
	if id == "" {
		writeError(w, http.StatusBadRequest, "missing id")
		return
	}

	snippet, err := h.snippetStore.GetByID(r.Context(), id)
	if err != nil {
		if errors.Is(err, store.ErrNotFound) {
			writeError(w, http.StatusNotFound, "snippet not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "internal error")
		return
	}

	if snippet.UserID != userID {
		writeError(w, http.StatusForbidden, "forbidden")
		return
	}

	if err := h.snippetStore.Delete(r.Context(), id); err != nil {
		if errors.Is(err, store.ErrNotFound) {
			writeError(w, http.StatusNotFound, "snippet not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "internal error")
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

func extractID(r *http.Request) string {
	if id := r.PathValue("id"); id != "" {
		return id
	}
	path := strings.TrimPrefix(r.URL.Path, "/snippets/")
	path = strings.TrimSuffix(path, "/")
	return path
}