package main

import (
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
)

// applyReplaceAllPatch performs global string replacements in all files
func applyReplaceAllPatch(rootPath string, modifications []string) error {
	replacements := [][2]string{}
	for _, mod := range modifications {
		parts := strings.SplitN(mod, "=>", 2)
		if len(parts) != 2 {
			continue
		}
		from := strings.TrimSpace(parts[0])
		to := strings.TrimSpace(parts[1])
		replacements = append(replacements, [2]string{from, to})
	}

	// Get absolute path of the patcher's own directory
	selfPath, err := os.Executable()
	if err != nil {
		return fmt.Errorf("cannot resolve own path: %v", err)
	}
	patcherDir := filepath.Dir(selfPath)

	return filepath.WalkDir(rootPath, func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}

		// Skip patcher's own dir and subdirs
		if strings.HasPrefix(path, patcherDir) {
			if d.IsDir() {
				return fs.SkipDir
			}
			return nil
		}

		// Skip any obj-* folders inside mozilla-release
		if strings.Contains(path, "mozilla-release/obj-") {
			if d.IsDir() {
				return fs.SkipDir
			}
			return nil
		}

		if d.IsDir() {
			return nil
		}

		// Only patch known text/code files
		if strings.HasSuffix(path, ".cpp") || strings.HasSuffix(path, ".h") ||
			strings.HasSuffix(path, ".c") || strings.HasSuffix(path, ".go") ||
			strings.HasSuffix(path, ".js") || strings.HasSuffix(path, ".ts") ||
			strings.HasSuffix(path, ".html") || strings.HasSuffix(path, ".in") ||
			strings.HasSuffix(path, ".mjs") || strings.HasSuffix(path, ".txt") {
			return replaceInFile(path, replacements)
		}
		return nil
	})
}

// replaceInFile performs replacements in one file
func replaceInFile(filePath string, replacements [][2]string) error {
	content, err := os.ReadFile(filePath)
	if err != nil {
		return err
	}
	text := string(content)
	original := text

	for _, repl := range replacements {
		text = strings.ReplaceAll(text, repl[0], repl[1])
	}

	if text != original {
		err = os.WriteFile(filePath, []byte(text), 0644)
		if err != nil {
			return fmt.Errorf("failed to write modified file: %v", err)
		}
		fmt.Printf("Replaced content in: %s\n", filePath)
	}
	return nil
}