package common

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

var gitHookNames = []string{
	"pre-receive", "update", "post-receive", "post-update", "proc-receive",
	"push-to-checkout", "reference-transaction", "pre-applypatch",
	"post-applypatch", "pre-commit", "pre-merge-commit", "prepare-commit-msg",
	"commit-msg", "post-commit", "pre-rebase", "post-checkout", "post-merge",
	"pre-push", "pre-auto-gc", "post-rewrite", "sendemail-validate",
	"fsmonitor-watchman", "p4-pre-submit", "p4-post-changelist",
	"p4-prepare-changelist", "p4-changelist",
}

const hookWrapper = `#!/bin/sh
# Generated by simplegit. The operator controls hook behavior with -hook-script.
test -n "$SIMPLEGIT_HOOK_SCRIPT" || exit 0
repo_dir=$(pwd -P)
repo=${repo_dir#"$SIMPLEGIT_REPO_ROOT"/}
repo=${repo%%.git}
exec "$SIMPLEGIT_HOOK_SCRIPT" %s "$repo" "$@"
`

// EnsureHookTemplate creates the git-init template used for new repositories.
// All hook entrypoints delegate to one environment-specific external script.
func EnsureHookTemplate(root string) (string, error) {
	dir := filepath.Join(root, "template")
	hooksDir := filepath.Join(dir, "hooks")
	if err := os.MkdirAll(hooksDir, 0o755); err != nil {
		return "", fmt.Errorf("create hook template: %w", err)
	}
	for _, name := range gitHookNames {
		path := filepath.Join(hooksDir, name)
		if err := os.WriteFile(path, []byte(fmt.Sprintf(hookWrapper, name)), 0o755); err != nil {
			return "", fmt.Errorf("write hook %s: %w", name, err)
		}
	}
	if err := refreshRepositoryHooks(filepath.Join(root, "repos"), hooksDir); err != nil {
		return "", err
	}
	return dir, nil
}

// refreshRepositoryHooks updates repositories created with an older template.
func refreshRepositoryHooks(reposRoot, templateHooks string) error {
	if _, err := os.Stat(reposRoot); os.IsNotExist(err) {
		return nil
	}
	return filepath.WalkDir(reposRoot, func(path string, entry fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if !entry.IsDir() || !strings.HasSuffix(entry.Name(), ".git") {
			return nil
		}
		dst := filepath.Join(path, "hooks")
		if err := os.MkdirAll(dst, 0o755); err != nil {
			return err
		}
		for _, name := range gitHookNames {
			body, err := os.ReadFile(filepath.Join(templateHooks, name))
			if err != nil {
				return err
			}
			if err := os.WriteFile(filepath.Join(dst, name), body, 0o755); err != nil {
				return err
			}
		}
		return filepath.SkipDir
	})
}