package tasks

import (
	"context"
	"errors"
	"os"
	"strings"

	"charm.land/huh/v2"
	"github.com/LazyBachelor/LazyPM/internal/models"
	"github.com/LazyBachelor/LazyPM/internal/utils/check"
	"github.com/go-git/go-git/v6"
)

const gitTaskDescription = `You are tasked with performing a Git operation.

Modify a file in a Git repository and commit the change.

Your task:
1. Assign the given issue to yourself as 'Me'.
2. A folder called "task" is created in this directory.
3. Inside the folder you will find README.md.
   - Edit this file and add something to it.
   - The file must be different from its original content.
4. Commit your change:
   - Open a terminal and change into the task folder.
   - Run "git add ." to stage the changes.
   - Run "git commit -m "updated codebase"" to commit.
5. Set the Issue status to "Closed" when done.

The repository is in the task folder (./task).`

const gitTaskReadmeContent = "This is a Git task. Add your name or a short note below this line to complete it, then commit your change."

type GitTask struct {
	app        *App
	done       bool
	repo       *git.Repository
	setupIssue *Issue
}

var gitTaskInProgress = false

func NewGitTask(app *App) *GitTask {
	return &GitTask{app: app, done: false}
}

func (t *GitTask) Config() Config {
	return BaseConfig().WithStatisticsStoragePath("./.pm/git-task-stats.json")
}

func (t *GitTask) Details(interfaceType InterfaceType) TaskDetails {
	return BaseDetails(interfaceType).
		WithTitle("Git Task").
		WithDescription(gitTaskDescription).
		WithDifficulty("Hard").WithTimeToComplete("5m")
}

func (t *GitTask) Questions(interfaceType InterfaceType) Questions {
	return BaseQuestions(interfaceType).
		With(
			huh.NewGroup(
				huh.NewSelect[string]().Key("git_interface_normally").
					Title("What Git Interface do you normally use?").
					Description("If you regularly use multiple interfaces, select the one you prefer most.").
					Options(
						huh.Option[string]{Value: "cli", Key: "Command Line Interface"},
						huh.Option[string]{Value: "tui", Key: "Terminal User Interface"},
						huh.Option[string]{Value: "gui", Key: "Graphical User Interface"},
					),
			))
}

func (t *GitTask) QuestionnaireKeys(_ InterfaceType) []string {
	return BaseKeys().With("git_interface_normally")
}

func (t *GitTask) Setup(ctx context.Context) error {
	gitTaskInProgress = false
	if err := ClearIssues(t.app); err != nil {
		return err
	}

	_ = os.RemoveAll("./task")

	var err error
	t.repo, err = t.initRepo()
	if err != nil {
		return err
	}

	_ = os.WriteFile("./task/README.md", []byte(gitTaskReadmeContent), 0o644)
	_ = os.WriteFile("./task/.gitattributes", []byte("* text=auto\n"), 0o644)

	t.setupIssue = NewIssueBuilder().
		WithTitle("Upgrade the codebase").
		WithDescription(gitTaskDescription).
		WithIssueType(models.TypeTask).
		Build()

	if err := t.app.Issues.CreateIssue(ctx, t.setupIssue, ""); err != nil {
		return err
	}

	return nil
}

func (t *GitTask) Validate(ctx context.Context) ValidationFeedback {
	expect := check.NewExpector()

	issue, err := t.app.Issues.GetIssue(ctx, t.setupIssue.ID)
	if err != nil {
		return expect.Fatal("Could not fetch issue")
	}
	if issue == nil {
		expect.Fail("Issue could not be found. It may have been deleted; please recreate it and try again.")
		return expect.ValidationFeedback
	}

	expect.Equal(issue.Assignee, "Me", "Issue Assignee")

	if !expect.Valid() {
		return expect.ValidationFeedback
	}

	// Ensure the repository is available.
	if t.repo == nil {
		t.repo, err = t.initRepo()
		if err != nil {
			expect.Fail("Failed to open the Git repository: " + err.Error())
			return expect.ValidationFeedback
		}
	}

	headRef, err := t.repo.Head()
	if err != nil {
		expect.Fail("No commits found in the Git repository. Please commit your changes.")
		return expect.ValidationFeedback
	}

	commit, err := t.repo.CommitObject(headRef.Hash())
	if err != nil {
		expect.Fail("Failed to read the latest commit: " + err.Error())
		return expect.ValidationFeedback
	}

	expect.NotEmptyAndEqual(strings.TrimSpace(commit.Message), "updated codebase", "Git commit message")

	tree, err := commit.Tree()
	if err != nil {
		expect.Fail("Failed to read commit tree: " + err.Error())
		return expect.ValidationFeedback
	}

	readmeFile, err := tree.File("README.md")
	if err != nil {
		expect.Fail("README.md should be part of the committed changes.")
		return expect.ValidationFeedback
	}

	readmeContent, err := readmeFile.Contents()
	if err != nil {
		expect.Fail("Failed to read README.md from the commit: " + err.Error())
		return expect.ValidationFeedback
	}

	expect.Assert(readmeContent != gitTaskReadmeContent,
		"You should modify README.md content before committing")

	if wt, err := t.repo.Worktree(); err == nil {
		if status, err := wt.Status(); err == nil {
			expect.Assert(status.IsClean(), "The working tree should be clean after committing")
		}
	}

	if !expect.Valid() {
		return expect.ValidationFeedback
	}

	expect.Equal(issue.Status, models.StatusClosed, "Issue Status")

	return expect.Complete()
}

func (t *GitTask) initRepo() (*git.Repository, error) {
	repo, err := git.PlainInit("./task", false)
	if err != nil {
		if errors.Is(err, git.ErrTargetDirNotEmpty) {
			repo, err = git.PlainOpen("./task")
			if err != nil {
				return nil, err
			}
			return repo, nil
		}
		return nil, err
	}
	return repo, nil
}