// mmc -- Mattermost client
// Copyright (C) 2023-2024 Sergey Matveev <stargrave@stargrave.org>
//
// 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.
//
// 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 <http://www.gnu.org/licenses/>.

package main

import (
	"net/http"
	"os"
	"os/exec"
	"path"
	"strings"
	"time"

	"github.com/davecgh/go-spew/spew"
	"github.com/mattermost/mattermost-server/v6/model"
	"go.cypherpunks.ru/recfile"
	"go.stargrave.org/mmc/internal"
)

const CmdFile = "/FILE "

func writePosts(where string, users map[string]*model.User, posts []mmc.Post) error {
	if len(posts) == 0 {
		return nil
	}
	unlock, err := mmc.Lock(path.Join(where, mmc.OutRecLock))
	if err != nil {
		return err
	}
	defer unlock()
	fd, err := os.OpenFile(
		path.Join(where, mmc.OutRec),
		os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o666,
	)
	if err != nil {
		return err
	}
	defer fd.Close()
	w := recfile.NewWriter(fd)
	var lastPostId string
	for _, post := range posts {
		if err = mmc.PostToRec(w, users, post); err != nil {
			return err
		}
		lastPostId = post.P.Id
	}
	tmp, err := os.CreateTemp(where, "last")
	if err != nil {
		return err
	}
	err = os.Chmod(tmp.Name(), os.FileMode(0666&^UmaskCur))
	if err != nil {
		tmp.Close()
		os.Remove(tmp.Name())
		return err
	}
	if _, err = tmp.WriteString(lastPostId + "\n"); err != nil {
		os.Remove(tmp.Name())
		tmp.Close()
		return err
	}
	if err = tmp.Close(); err != nil {
		os.Remove(tmp.Name())
		return err
	}
	if err = os.Rename(tmp.Name(), path.Join(where, mmc.Last)); err != nil {
		os.Remove(tmp.Name())
		return err
	}
	unlock()
	if *Newwin != "" {
		exec.Command(*Newwin, where).Run()
	}
	return nil
}

func updatePosts(c *model.Client4, users map[string]*model.User, where, chId string) error {
	data, err := os.ReadFile(path.Join(where, mmc.Last))
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}
	lastPostId := strings.TrimRight(string(data), "\n")
	if lastPostId == "" {
		return nil
	}
	for n := 0; ; n++ {
		time.Sleep(mmc.SleepTime)
		list, resp, err := c.GetPostsAfter(
			chId, lastPostId, n, mmc.PerPage, "", false,
		)
		if DebugFd != nil {
			spew.Fdump(DebugFd, list, resp)
		}
		if resp.StatusCode == http.StatusNotFound {
			break
		}
		if err != nil {
			return err
		}
		var posts []mmc.Post
		for _, post := range list.ToSlice() {
			posts = append(posts, mmc.Post{P: post, E: model.WebsocketEventPosted})
		}
		if err = writePosts(where, users, posts); err != nil {
			return err
		}
		if len(posts) < mmc.PerPage {
			break
		}
	}
	return nil
}

func makePost(c *model.Client4, chId, text string) (*model.Post, error) {
	text = strings.TrimRight(text, " \n")
	if text == "" {
		return nil, nil
	}
	post := &model.Post{ChannelId: chId}
	var lines []string
	for _, line := range strings.Split(text, "\n") {
		if !strings.HasPrefix(line, CmdFile) {
			lines = append(lines, line)
			continue
		}
		fn := strings.TrimPrefix(line, CmdFile)
		data, err := os.ReadFile(fn)
		if err != nil {
			return nil, err
		}
		resp, _, err := c.UploadFile(data, chId, path.Base(fn))
		if err != nil {
			return nil, err
		}
		post.FileIds = append(post.FileIds, resp.FileInfos[0].Id)
	}
	post.Message = strings.Join(lines, "\n")
	post, _, err := c.CreatePost(post)
	return post, err
}