// Copyright 2025 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package repo

import (
	"context"
	"fmt"
	"path"
	"strings"

	git_model "code.gitea.io/gitea/models/git"
	repo_model "code.gitea.io/gitea/models/repo"
	"code.gitea.io/gitea/modules/git"
	"code.gitea.io/gitea/modules/json"
	"code.gitea.io/gitea/modules/log"
	context_service "code.gitea.io/gitea/services/context"
)

// getUniquePatchBranchName Gets a unique branch name for a new patch branch
// It will be in the form of <username>-patch-<num> where <num> is the first branch of this format
// that doesn't already exist. If we exceed 1000 tries or an error is thrown, we just return "" so the user has to
// type in the branch name themselves (will be an empty field)
func getUniquePatchBranchName(ctx context.Context, prefixName string, repo *repo_model.Repository) string {
	prefix := prefixName + "-patch-"
	for i := 1; i <= 1000; i++ {
		branchName := fmt.Sprintf("%s%d", prefix, i)
		if exist, err := git_model.IsBranchExist(ctx, repo.ID, branchName); err != nil {
			log.Error("getUniquePatchBranchName: %v", err)
			return ""
		} else if !exist {
			return branchName
		}
	}
	return ""
}

// getClosestParentWithFiles Recursively gets the closest path of parent in a tree that has files when a file in a tree is
// deleted. It returns "" for the tree root if no parents other than the root have files.
func getClosestParentWithFiles(gitRepo *git.Repository, branchName, originTreePath string) string {
	var f func(treePath string, commit *git.Commit) string
	f = func(treePath string, commit *git.Commit) string {
		if treePath == "" || treePath == "." {
			return ""
		}
		// see if the tree has entries
		if tree, err := commit.SubTree(treePath); err != nil {
			return f(path.Dir(treePath), commit) // failed to get the tree, going up a dir
		} else if entries, err := tree.ListEntries(); err != nil || len(entries) == 0 {
			return f(path.Dir(treePath), commit) // no files in this dir, going up a dir
		}
		return treePath
	}
	commit, err := gitRepo.GetBranchCommit(branchName) // must get the commit again to get the latest change
	if err != nil {
		log.Error("GetBranchCommit: %v", err)
		return ""
	}
	return f(originTreePath, commit)
}

// getContextRepoEditorConfig returns the editorconfig JSON string for given treePath or "null"
func getContextRepoEditorConfig(ctx *context_service.Context, treePath string) string {
	ec, _, err := ctx.Repo.GetEditorconfig()
	if err == nil {
		def, err := ec.GetDefinitionForFilename(treePath)
		if err == nil {
			jsonStr, _ := json.Marshal(def)
			return string(jsonStr)
		}
	}
	return "null"
}

// getParentTreeFields returns list of parent tree names and corresponding tree paths based on given treePath.
// eg: []{"a", "b", "c"}, []{"a", "a/b", "a/b/c"}
// or: []{""}, []{""} for the root treePath
func getParentTreeFields(treePath string) (treeNames, treePaths []string) {
	treeNames = strings.Split(treePath, "/")
	treePaths = make([]string, len(treeNames))
	for i := range treeNames {
		treePaths[i] = strings.Join(treeNames[:i+1], "/")
	}
	return treeNames, treePaths
}