package gitops

import (
	"context"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
)

type Credentials struct {
	Username string
	Secret   string
}

type Runner struct{}

func New() *Runner {
	return &Runner{}
}

func (r *Runner) CheckAvailable() error {
	_, err := exec.LookPath("git")
	return err
}

func (r *Runner) Clone(ctx context.Context, remoteURL, dest string, creds Credentials) error {
	if err := os.MkdirAll(filepath.Dir(dest), 0o755); err != nil {
		return err
	}
	return r.run(ctx, "", creds, "clone", remoteURL, dest)
}

func (r *Runner) Pull(ctx context.Context, repoPath string, creds Credentials) error {
	return r.run(ctx, repoPath, creds, "pull", "--ff-only")
}

func (r *Runner) Fetch(ctx context.Context, repoPath string, creds Credentials) error {
	return r.run(ctx, repoPath, creds, "fetch", "origin")
}

func (r *Runner) CurrentCommit(repoPath string) (string, error) {
	return r.output(context.Background(), repoPath, Credentials{}, "rev-parse", "HEAD")
}

func (r *Runner) RemoteCommit(ctx context.Context, repoPath, branch string, creds Credentials) (string, error) {
	out, err := r.output(ctx, repoPath, creds, "ls-remote", "origin", "refs/heads/"+branch)
	if err != nil {
		return "", err
	}
	fields := strings.Fields(out)
	if len(fields) == 0 {
		return "", fmt.Errorf("remote branch %s not found", branch)
	}
	return fields[0], nil
}

func (r *Runner) HasLocalChanges(repoPath string) (bool, error) {
	out, err := r.output(context.Background(), repoPath, Credentials{}, "status", "--porcelain")
	if err != nil {
		return false, err
	}
	return strings.TrimSpace(out) != "", nil
}

func (r *Runner) run(ctx context.Context, dir string, creds Credentials, args ...string) error {
	out, err := r.command(ctx, dir, creds, args...).CombinedOutput()
	if err != nil {
		return fmt.Errorf("git %s failed: %w: %s", strings.Join(args, " "), err, strings.TrimSpace(string(out)))
	}
	return nil
}

func (r *Runner) output(ctx context.Context, dir string, creds Credentials, args ...string) (string, error) {
	out, err := r.command(ctx, dir, creds, args...).CombinedOutput()
	if err != nil {
		return "", fmt.Errorf("git %s failed: %w: %s", strings.Join(args, " "), err, strings.TrimSpace(string(out)))
	}
	return strings.TrimSpace(string(out)), nil
}

func (r *Runner) command(ctx context.Context, dir string, creds Credentials, args ...string) *exec.Cmd {
	fullArgs := append([]string{"-c", "credential.helper=", "-c", "credential.useHttpPath=true"}, args...)
	cmd := exec.CommandContext(ctx, "git", fullArgs...)
	cmd.Dir = dir
	cmd.Env = append(os.Environ(), "GIT_TERMINAL_PROMPT=0")
	if creds.Username != "" || creds.Secret != "" {
		scriptPath := askPassScript()
		_ = ensureAskPassScript(scriptPath)
		cmd.Env = append(
			cmd.Env,
			"GIT_ASKPASS="+scriptPath,
			"GITEA_USERNAME="+creds.Username,
			"GITEA_PASSWORD="+creds.Secret,
		)
	}
	return cmd
}

func askPassScript() string {
	return filepath.Join(os.TempDir(), "sgg-ai-skill-manager-git-askpass.cmd")
}

func ensureAskPassScript(path string) error {
	content := "@echo off\r\nset prompt=%~1\r\necho %prompt% | findstr /I \"username\" >nul\r\nif %ERRORLEVEL%==0 (echo %GITEA_USERNAME%) else (echo %GITEA_PASSWORD%)\r\n"
	return os.WriteFile(path, []byte(content), 0o600)
}