// s3staticsites: servers http requests from an S3 bucket
// Copyright (C) 2024 Finn Herzfeld

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.

// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package main

import (
	"context"
	"io"
	"net/http"
	"strings"

	minio "github.com/minio/minio-go/v7"
	"golang.org/x/exp/slog"
)

func ListenAndServe(minioClient *minio.Client) error {
	slog.Info("starting http server", "bind", config.Bind)
	err := http.ListenAndServe(config.Bind, handler{minio: minioClient})
	if err != nil {
		return err
	}

	return nil
}

type handler struct {
	minio *minio.Client
}

func (h handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	domain := r.Host
	path := r.URL.Path
	if path == "" || path == "/" {
		path = "index.html"
	}

	object, stat, err := h.get(r.Context(), domain, path)
	if err != nil {
		resp := minio.ToErrorResponse(err)
		if resp.StatusCode == http.StatusNotFound {
			// TODO: custom 404 page
			w.WriteHeader(http.StatusNotFound)
			w.Write([]byte("404 not found"))
			slog.Info("served 404", "domain", domain, "path", path)
			return
		}
		slog.Error("error getting object from storage", "bucket", domain, "object", path, "err", err)
		http.Error(w, "internal server error", http.StatusInternalServerError)
		return
	}

	w.Header().Add("Content-Type", stat.ContentType)
	w.Header().Add("ETag", stat.ETag)

	n, err := io.Copy(w, object)
	if err != nil {
		slog.Warn("error writting response", "error", err, "domain", domain, "path", path)
		return
	}

	slog.Info("served request", "domain", domain, "path", path, "size_bytes", n)
}

func (h handler) get(ctx context.Context, bucket string, path string) (*minio.Object, *minio.ObjectInfo, error) {
	object, err := h.minio.GetObject(ctx, bucket, path, minio.GetObjectOptions{})
	if err != nil {
		return nil, nil, err
	}

	stat, err := object.Stat()
	if err != nil {
		resp := minio.ToErrorResponse(err)
		if resp.StatusCode == http.StatusNotFound {
			if strings.HasSuffix(path, "/index.html") {
				return nil, nil, err
			}
			if !strings.HasSuffix(path, "/") {
				path = path + "/"
			}
			path = path + "index.html"
			return h.get(ctx, bucket, path)
		}

		return nil, nil, err
	}

	return object, &stat, nil
}