package mergeconflicts

import (
	"regexp"
	"strings"

	"github.com/jesseduffield/lazygit/pkg/utils"
)

// LineType tells us whether a given line is a start/middle/end marker of a conflict,
// or if it's not a marker at all
type LineType int

const (
	START LineType = iota
	MIDDLE
	END
	NOT_A_MARKER
)

func findConflicts(content string) []*mergeConflict {
	conflicts := make([]*mergeConflict, 0)

	if content == "" {
		return conflicts
	}

	var newConflict *mergeConflict
	for i, line := range utils.SplitLines(content) {
		switch determineLineType(line) {
		case START:
			newConflict = &mergeConflict{start: i}
		case MIDDLE:
			newConflict.middle = i
		case END:
			newConflict.end = i
			conflicts = append(conflicts, newConflict)
		default:
			// line isn't a merge conflict marker so we just continue
		}
	}

	return conflicts
}

func determineLineType(line string) LineType {
	trimmedLine := strings.TrimPrefix(line, "++")

	mapping := map[string]LineType{
		"^<<<<<<< (HEAD|MERGE_HEAD|Updated upstream|ours)(:.+)?$": START,
		"^=======$":    MIDDLE,
		"^>>>>>>> .*$": END,
	}

	for regexp_str, lineType := range mapping {
		match, _ := regexp.MatchString(regexp_str, trimmedLine)
		if match {
			return lineType
		}
	}

	return NOT_A_MARKER
}