package gitw

import (
	"errors"
	"fmt"

	"gitea.yves-biener.de/yves-biener/gitwarrior/internal/gitea"
	"gitea.yves-biener.de/yves-biener/gitwarrior/internal/taskwarrior"
)

type Project struct {
	server     gitea.Gitea
	repository gitea.Repository
	issues     []Issue
	milestones []gitea.Milestone
}

func NewProject(server gitea.Gitea, repository gitea.Repository) Project {
	return Project{
		server:     server,
		repository: repository,
	}
}

func (project *Project) Pull() error {
	if err := project.Fetch(); err != nil {
		return err
	}
	if err := project.merge(); err != nil {
		return err
	}
	return nil
}

func (project *Project) Fetch() error {
	comments, err := project.server.GetComments(project.repository)
	if err != nil {
		return err
	}
	issues, err := project.server.GetIssues(project.repository)
	if err != nil {
		return err
	}
	project.milestones, err = project.server.GetMilestones(project.repository)
	if err != nil {
		return err
	}
	for _, issue := range issues {
		var issue_comments []gitea.Comment
		for _, comment := range comments {
			if comment.Issue_url == issue.Html_url {
				issue_comments = append(issue_comments, comment)
			}
		}
		project.issues = append(project.issues, Issue{
			git_issue: issue,
			comments:  issue_comments,
		})
	}
	return nil
}

// TODO: tasks should include the corresponding time's of the git related issues and milestones
func (project *Project) merge() error {
	var tasks []taskwarrior.Task
	var filter taskwarrior.Filter
	// TODO: merge milestones
	for _, milestone := range project.milestones {
		filter.Reset()
		filter.IncludeGitId(milestone.Id)
		filter.IncludeGitType(taskwarrior.MILESTONE)
		git_tasks, err := taskwarrior.GetTasks(filter)
		if err != nil {
			return err
		}
		var task taskwarrior.Task
		if len(git_tasks) > 1 {
			return errors.New("Git milestone id was at least used twice in taskwarrior tasks.")
		} else if len(git_tasks) == 0 {
			// NOTE: ignore closed milestones which do not have a taskwarrior task
			if milestone.State == string(gitea.CLOSED) {
				continue
			}
			// NOTE: this milestone does not yet exist
			task = taskwarrior.NewTask(
				milestone.Title,
				project.repository.Name,
				milestone.Id,
				taskwarrior.MILESTONE,
			)
			task.Due = taskwarrior.GoTimeToTaskTime(milestone.Due_on)
			task.Entry = taskwarrior.GoTimeToTaskTime(milestone.Created_at)
			task.Modified = taskwarrior.GoTimeToTaskTime(milestone.Updated_at)
			task.AppendComment(milestone.Description, milestone.Updated_at)
			fmt.Printf("\tCreated milestone: '%s'\n", task.Description)
			tasks = append(tasks, task)
		} else {
			// NOTE: there is exactly one git_task
			task = milestone.Merge(git_tasks[0])
			fmt.Printf("\tUpdated milestone: '%s'\n", task.Description)
			tasks = append(tasks, task)
		}
	}
	// NOTE: merge tasks
	// TODO: link milestones into tasks
	for _, issue := range project.issues {
		filter.Reset()
		filter.IncludeGitId(issue.git_issue.Id)
		filter.IncludeGitType(taskwarrior.ISSUE)
		git_tasks, err := taskwarrior.GetTasks(filter)
		if err != nil {
			return err
		}
		var task taskwarrior.Task
		if len(git_tasks) > 1 {
			return errors.New("Git issue id was at least used twice in taskwarrior tasks.")
		} else if len(git_tasks) == 0 {
			// NOTE: ignore closed issues which do not have a taskwarrior task
			if issue.git_issue.State == string(gitea.CLOSED) {
				continue
			}
			// NOTE: this task does not yet exist
			task = taskwarrior.NewTask(
				issue.git_issue.Title,
				project.repository.Name,
				issue.git_issue.Id,
				taskwarrior.ISSUE,
				issue.git_issue.Labels...,
			)
			task.Entry = taskwarrior.GoTimeToTaskTime(issue.git_issue.Created_at)
			task.Modified = taskwarrior.GoTimeToTaskTime(issue.git_issue.Updated_at)
			for _, comment := range issue.comments {
				task.AppendComment(comment.Body, comment.Updated_at)
			}
			fmt.Printf("\tCreated task: '%s'\n", task.Description)
			tasks = append(tasks, task)
		} else {
			// NOTE: there is excactly one git_task
			task = issue.merge(git_tasks[0])
			fmt.Printf("\tUpdated task: '%s'\n", task.Description)
			tasks = append(tasks, task)
		}
	}
	// TODO: dry-run switch
	if false {
		return taskwarrior.UpdateTasks(tasks)
	}
	return nil
}

type Issue struct {
	git_issue gitea.Issue
	comments  []gitea.Comment
}

func (i *Issue) into() (taskwarrior.Task, error) {
	// TODO: identify if issue is already an existing task
	var filter taskwarrior.Filter
	filter.IncludeGitId(i.git_issue.Id)
	filter.IncludeGitType(taskwarrior.ISSUE)
	tasks, err := taskwarrior.GetTasks(filter)
	if err != nil {
		// this means that a task for this issue does not exist yet
		return taskwarrior.NewTask(
			i.git_issue.Title,
			i.git_issue.Repository.Name,
			i.git_issue.Id,
			taskwarrior.ISSUE,
			i.git_issue.Labels...,
		), nil
	} else {
		// this means that a task exists and it needs to be merged
		if len(tasks) != 1 {
			return taskwarrior.Task{}, errors.New("Did not find exactly one task for a given issue.Id")
		}
		return i.merge(tasks[0]), nil
	}
}

// TODO: implement merging of git issue or milestone into a taskwarrior task
func (i *Issue) merge(task taskwarrior.Task) taskwarrior.Task {
	// TODO: issue values into task:
	// - is the issue more recent than the task?
	// - apply changes into task
	// - in case of merge conflicts ask user for corresponding action:
	//     1. use theirs
	//     2. use mine
	//     3. use provided value
	return task
}