package main

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

func writeJSON(w http.ResponseWriter, code int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	_ = json.NewEncoder(w).Encode(v)
}

func jsonError(w http.ResponseWriter, code int, msg string) {
	writeJSON(w, code, map[string]string{"error": msg})
}

// healthz — for k8s probes / load balancer.
func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, 200, map[string]string{"status": "ok"})
}

func (s *Server) handleListPosts(w http.ResponseWriter, r *http.Request) {
	channel := r.URL.Query().Get("channel")
	posts, err := s.store.ListPosts(channel, 20)
	if err != nil {
		jsonError(w, 500, err.Error())
		return
	}
	if posts == nil {
		posts = []Post{} // never return null to clients
	}
	writeJSON(w, 200, map[string]any{"posts": posts})
}

func (s *Server) handleGetPost(w http.ResponseWriter, r *http.Request) {
	id := strings.TrimPrefix(r.URL.Path, "/api/posts/")
	if id == "" || strings.Contains(id, "/") {
		jsonError(w, 400, "bad id")
		return
	}
	post, err := s.store.GetPost(id)
	if err != nil {
		jsonError(w, 404, "not found")
		return
	}
	comments, err := s.store.ListComments(id)
	if err != nil {
		jsonError(w, 500, err.Error())
		return
	}
	if comments == nil {
		comments = []Comment{}
	}
	writeJSON(w, 200, PostWithComments{Post: *post, Comments: comments})
}

func (s *Server) handleCreatePost(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		jsonError(w, 405, "POST only")
		return
	}
	author := r.Header.Get("X-Posts-Author")
	if author == "" {
		jsonError(w, 401, "X-Posts-Author required (v0: no auth, just header)")
		return
	}
	var req CreatePostRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonError(w, 400, "bad json")
		return
	}
	if strings.TrimSpace(req.Body) == "" {
		jsonError(w, 400, "body required")
		return
	}
	post, err := s.store.CreatePost(author, req.Title, req.Body, req.Channels)
	if err != nil {
		jsonError(w, 500, err.Error())
		return
	}
	writeJSON(w, 201, post)
}

func (s *Server) handleCreateComment(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		jsonError(w, 405, "POST only")
		return
	}
	author := r.Header.Get("X-Posts-Author")
	if author == "" {
		jsonError(w, 401, "X-Posts-Author required")
		return
	}
	// path: /api/posts/:id/comments
	parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
	// expected: ["api","posts",":id","comments"]
	if len(parts) != 4 {
		jsonError(w, 400, "bad path")
		return
	}
	postID := parts[2]
	var req CreateCommentRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonError(w, 400, "bad json")
		return
	}
	if strings.TrimSpace(req.Body) == "" {
		jsonError(w, 400, "body required")
		return
	}
	c, err := s.store.AddComment(postID, req.ParentID, author, req.Body)
	if err != nil {
		jsonError(w, 400, err.Error())
		return
	}
	writeJSON(w, 201, c)
}