package handlers

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

	"opds-explorer/internal/proxy"
)

type Handler struct {
	proxy proxyClient
}

type proxyClient interface {
	Fetch(method, targetURL string, headers http.Header, body []byte) (*proxy.FetchResult, error)
}

func New(p proxyClient) *Handler {
	return &Handler{proxy: p}
}

// FetchFeed handles GET/POST /api/fetch?url=... or JSON body { "url": "...", "method": "GET", "headers": {}, "body": "" }
func (h *Handler) FetchFeed(w http.ResponseWriter, r *http.Request) {
	var method, targetURL string
	var headers http.Header
	var body []byte

	if r.Method == http.MethodPost {
		var req struct {
			URL     string            `json:"url"`
			Method  string            `json:"method"`
			Headers map[string]string `json:"headers"`
			Body    string            `json:"body"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			http.Error(w, "invalid JSON body", http.StatusBadRequest)
			return
		}
		targetURL = req.URL
		method = req.Method
		if method == "" {
			method = "GET"
		}
		headers = make(http.Header)
		for k, v := range req.Headers {
			headers.Set(k, v)
		}
		body = []byte(req.Body)
	} else {
		targetURL = r.URL.Query().Get("url")
		method = r.Method
	}

	if targetURL == "" {
		http.Error(w, "missing url", http.StatusBadRequest)
		return
	}

	result, err := h.proxy.Fetch(method, targetURL, headers, body)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	_ = json.NewEncoder(w).Encode(result)
}

// ProxyResource streams a GET request to the given url (e.g. for images). Requires proxyClientStream interface.
func (h *Handler) ProxyResource(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}
	targetURL := r.URL.Query().Get("url")
	if targetURL == "" {
		http.Error(w, "missing url", http.StatusBadRequest)
		return
	}
	streamer, ok := h.proxy.(interface {
		ProxyStream(string, http.ResponseWriter) (int, error)
	})
	if !ok {
		http.Error(w, "proxy does not support streaming", http.StatusInternalServerError)
		return
	}
	_, err := streamer.ProxyStream(targetURL, w)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadGateway)
	}
}