/*
 filter --- Simple interactive data filter for POSIX pipelines

Copyright (c) 2022  Sameer Rahmani <lxsameer@gnu.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
)

type Item struct {
	Text     string
	Selected bool
}

type Items = *[]*Item

func NewItem(text string) *Item {
	return &Item{
		Text:     text,
		Selected: false,
	}
}

func toggleItems(items Items, start int, end int) {
	for _, item := range (*items)[start:end] {
		item.Selected = !item.Selected
	}
}

// Pffff Golang, right? :D
func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

// Reads the input from stdin and makes sure that the current
// process is being run in a pipeline and converts the data
// to an array of items.
func ReadFromStdin() (Items, error) {
	info, err := os.Stdin.Stat()
	if err != nil {
		panic(err)
	}

	if info.Mode()&os.ModeCharDevice != 0 {
		return nil, fmt.Errorf("the command is intended to work with pipes. For example `git log | filter | xarg | ...`")
	}

	reader := bufio.NewReader(os.Stdin)
	var output []*Item

	for {
		input, _, err := reader.ReadLine()
		if err != nil && err == io.EOF {
			break
		}
		item := NewItem(string(input))
		output = append(output, item)
	}
	return &output, nil
}