package utils

import (
	"fmt"
	"modify/logger"
	"sort"
)

type ReplaceCommand struct {
	From int
	To   int
	With string
}

func ExecuteModifications(modifications []ReplaceCommand, fileData string) (string, int) {
	var err error

	sort.Slice(modifications, func(i, j int) bool {
		return modifications[i].From > modifications[j].From
	})
	logger.Trace("Applying %d replacement commands in reverse order", len(modifications))

	executed := 0
	for _, modification := range modifications {
		fileData, err = modification.Execute(fileData)
		if err != nil {
			logger.Error("Failed to execute modification: %v", err)
			continue
		}
		executed++
	}
	logger.Info("Executed %d modifications", executed)
	return fileData, executed
}

func (m *ReplaceCommand) Execute(fileDataStr string) (string, error) {
	err := m.Validate(len(fileDataStr))
	if err != nil {
		return "", fmt.Errorf("failed to validate modification: %v", err)
	}

	logger.Trace("Replace pos %d-%d with %q", m.From, m.To, m.With)
	return fileDataStr[:m.From] + m.With + fileDataStr[m.To:], nil
}

func (m *ReplaceCommand) Validate(maxsize int) error {
	if m.To < m.From {
		return fmt.Errorf("command to is less than from: %v", m)
	}
	if m.From > maxsize || m.To > maxsize {
		return fmt.Errorf("command from or to is greater than replacement length: %v", m)
	}
	return nil
}