package cmd

import (
	"bufio"
	"crypto/rand"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"text/template"

	"git.fernandovideira.com/FernandoJVideira/draft/assets"
)

const (
	chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_+"
)

func randomString(length int) string {
	s, r := make([]rune, length), []rune(chars)

	for i := range s {
		p, _ := rand.Prime(rand.Reader, len(r))
		x, y := p.Uint64(), uint64(len(r))
		s[i] = r[x%y]
	}
	return string(s)
}

func genFile(tplPath, tplName, outputPath string, data any) error {
	tplContent, err := assets.EmbedFS.ReadFile(tplPath)
	if err != nil {
		return fmt.Errorf("error reading %s template: %w", tplPath, err)
	}

	tpl, err := template.New(tplName).Parse(string(tplContent))
	if err != nil {
		return fmt.Errorf("error parsing %s template: %w", tplPath, err)
	}

	if err := os.MkdirAll(filepath.Dir(outputPath), 0o755); err != nil {
		return fmt.Errorf("error ensuring directory for %s: %w", outputPath, err)
	}

	outFile, err := os.Create(outputPath)
	if err != nil {
		return fmt.Errorf("error creating %s: %w", outputPath, err)
	}
	defer outFile.Close()

	return tpl.Execute(outFile, data)
}

func getModuleName() (string, error) {
	dir, err := os.Getwd()
	if err != nil {
		return "", fmt.Errorf("failed to get working directory: %w", err)
	}

	for {
		goModPath := filepath.Join(dir, "go.mod")
		file, err := os.Open(goModPath)
		if err == nil {
			defer file.Close()

			scanner := bufio.NewScanner(file)
			for scanner.Scan() {
				line := strings.TrimSpace(scanner.Text())
				if str, ok := strings.CutPrefix(line, "module "); ok {
					return strings.TrimSpace(str), nil
				}
			}
			if err := scanner.Err(); err != nil {
				return "", fmt.Errorf("failed to read %s: %w", goModPath, err)
			}
			return "", fmt.Errorf("module directive not found in %s", goModPath)
		}

		if !errors.Is(err, os.ErrNotExist) {
			return "", fmt.Errorf("failed to open %s: %w", goModPath, err)
		}

		parent := filepath.Dir(dir)
		if parent == dir {
			return "", fmt.Errorf("go.mod not found starting from %s", dir)
		}
		dir = parent
	}
}

func runCommand(dir, name string, args ...string) error {
	cmd := exec.Command(name, args...)
	cmd.Dir = dir
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	return cmd.Run()
}