package main

import (
	"encoding/csv"
	"encoding/json"
	"log"
	"net/http"
	"strconv"
	"strings"
)

// HandleListLinks handles GET /api/admin/links — returns all records.
func (h *Handler) HandleListLinks(w http.ResponseWriter, r *http.Request) {
	records, err := h.store.ListAll()
	if err != nil {
		log.Printf("list links error: %v", err)
		jsonError(w, "internal error", http.StatusInternalServerError)
		return
	}
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(records)
}

// HandleUpdateLink handles PUT /api/admin/links/{code} — updates a link's URL.
func (h *Handler) HandleUpdateLink(w http.ResponseWriter, r *http.Request) {
	code := r.PathValue("code")
	if code == "" {
		jsonError(w, "missing short code", http.StatusBadRequest)
		return
	}

	var req struct {
		URL string `json:"url"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		jsonError(w, "invalid request body", http.StatusBadRequest)
		return
	}

	req.URL = strings.TrimSpace(req.URL)
	if req.URL == "" {
		jsonError(w, "url is required", http.StatusBadRequest)
		return
	}
	if !strings.HasPrefix(req.URL, "http://") && !strings.HasPrefix(req.URL, "https://") {
		jsonError(w, "url must start with http:// or https://", http.StatusBadRequest)
		return
	}

	if err := h.store.Update(code, req.URL); err != nil {
		log.Printf("update link error: %v", err)
		jsonError(w, "short link not found", http.StatusNotFound)
		return
	}

	rec, _ := h.store.FindByCode(code)
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(rec)
}

// HandleDeleteLink handles DELETE /api/admin/links/{code} — deletes a link.
func (h *Handler) HandleDeleteLink(w http.ResponseWriter, r *http.Request) {
	code := r.PathValue("code")
	if code == "" {
		jsonError(w, "missing short code", http.StatusBadRequest)
		return
	}

	if err := h.store.Delete(code); err != nil {
		log.Printf("delete link error: %v", err)
		jsonError(w, "short link not found", http.StatusNotFound)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]bool{"ok": true})
}

// HandleExport handles GET /api/admin/export?format=json|csv — exports all data.
func (h *Handler) HandleExport(w http.ResponseWriter, r *http.Request) {
	records, err := h.store.ListAll()
	if err != nil {
		log.Printf("export error: %v", err)
		jsonError(w, "internal error", http.StatusInternalServerError)
		return
	}

	format := r.URL.Query().Get("format")
	if format == "csv" {
		w.Header().Set("Content-Type", "text/csv; charset=utf-8")
		w.Header().Set("Content-Disposition", "attachment; filename=\"shortlinks.csv\"")
		wr := csv.NewWriter(w)
		wr.Write([]string{"code", "original_url", "visit_count", "created_at"})
		for _, rec := range records {
			wr.Write([]string{
				rec.Code,
				rec.OriginalURL,
				strconv.FormatInt(rec.VisitCount, 10),
				rec.CreatedAt.UTC().Format("2006-01-02T15:04:05Z"),
			})
		}
		wr.Flush()
		return
	}

	w.Header().Set("Content-Type", "application/json")
	w.Header().Set("Content-Disposition", "attachment; filename=\"shortlinks.json\"")
	json.NewEncoder(w).Encode(records)
}