// Copyright (C) 2021 nytpu
// SPDX-License-Identifier: AGPL-3.0-or-later
// For more license details, see LICENSE or <https://www.gnu.org/licenses/agpl-3.0.html>.

// This file incorporates code from Drew DeVault's gemreader:
// https://git.sr.ht/~sircmpwn/gemreader/tree/master/item/feeds/fetch.go
// Original source is Copyright 2021 Drew DeVault and is licensed under the
// terms of the GNU Affero General Public License Version 3.0.
// https://www.gnu.org/licenses/agpl-3.0-standalone.html

package fetch

import (
	"context"
	"crypto/sha256"
	"fmt"
	"io"
	"net/http"
	"time"

	"github.com/mmcdole/gofeed"

	"golang.nytpu.com/comitium/core"
)

// fetchHTTP will make a request for an http resource
func fetchHTTP(remoteURL string) (*http.Response, error) {
	client := &http.Client{
		Timeout: 10 * time.Second,
	}

	req, err := http.NewRequestWithContext(context.Background(), "GET", remoteURL, nil)
	req.Header.Add("User-Agent", "comitium (https://git.nytpu.com/comitium/)")
	if err != nil {
		return nil, err
	}

	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}

	if resp.StatusCode != 200 {
		resp.Body.Close()
		return nil, fmt.Errorf("Unexpected HTTP response %s", resp.Status)
	}
	return resp, nil
}

// httpFeed will fetch and insert a new core.Feed into a core.FullData given an
// http url (or update if it's preexisting)
func httpFeed(data *core.FullData, remote string, title string) error {
	resp, err := fetchHTTP(remote)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.Header.Get("Content-Type") == "text/html" {
		// TODO
		return fmt.Errorf("Extracting feed from HTML pages is unimplemented")
	}

	reader := io.LimitReader(resp.Body, 1073741824) // 1 GiB
	gofeed, err := gofeed.NewParser().Parse(reader)
	if err != nil {
		return err
	}
	feed, err := core.GofeedConvert(gofeed, title)
	if err != nil {
		return err
	}

	data.InsertFeed(feed, remote)
	return nil
}

// httpPage will fetch and insert a new core.Page into a core.FullData given an
// http url (or update if it's preexisting)
func httpPage(data *core.FullData, remote string, title string) error {
	resp, err := fetchHTTP(remote)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	reader := io.LimitReader(resp.Body, 1073741824) // 1 GiB

	var page core.Page
	page.Title = title
	page.Link = remote
	h := sha256.New()
	if _, err := io.Copy(h, reader); err != nil {
		return err
	}
	newHash := fmt.Sprintf("%x", h.Sum(nil))
	page.Hash = newHash
	page.Updated = time.Now()

	data.InsertPage(&page, remote)
	return nil
}