package main

import (
	"errors"
	"time"
)

type Database interface {
	GetTracking() (*Entry, error)
	GetEntries() ([]*Entry, error)
	QueryEntry(id *int, date *Date) ([]*Entry, error)
	StartNewEntry(now time.Time, task *Entry) (*Entry, error)
	StopEntry(now time.Time) error
	SaveEntry(task *Entry) (*Entry, error)

	GetTasks() ([]*Task, error)
	QueryTask(id *int, group *string, ident *string) ([]*Task, error)
	SaveTask(task *Task) (*Task, error)
}

type InMemDb struct {
	entries []*Entry
	current *Entry
	tasks   []*Task
}

var (
	ErrNotFound   = errors.New("Not found")
	ErrNotRunning = errors.New("Not running")
)

func NewInMemDb() Database {
	return &InMemDb{
		entries: []*Entry{},
		current: nil,
	}
}

func (db *InMemDb) GetTracking() (*Entry, error) {
	return db.current, nil
}

func (db *InMemDb) GetEntries() ([]*Entry, error) {
	res := make([]*Entry, 0, len(db.entries))
	for _, task := range db.entries {
		res = append(res, task)
	}

	return res, nil
}

func (db *InMemDb) QueryEntry(id *int, date *Date) ([]*Entry, error) {
	res := make([]*Entry, 0, 1)
	for _, entry := range db.entries {
		if id != nil && entry.Id != *id {
			continue
		}
		if date != nil && entry.Date != *date {
			continue
		}
		res = append(res, entry)
	}

	return res, nil
}

func (db *InMemDb) StartNewEntry(now time.Time, task *Entry) (*Entry, error) {
	newTask := &Entry{
		Id:      len(db.entries),
		From:    task.From,
		To:      nil,
		Date:    DateFromStd(now),
		Tag:     task.Tag,
		Comment: task.Comment,
	}

	if newTask.From == nil {
		from := TimeFromStd(now)
		newTask.From = &from
	}

	db.entries = append(db.entries, newTask)
	db.StopEntry(now)
	db.current = newTask

	return newTask, nil
}

func (db *InMemDb) StopEntry(now time.Time) error {
	if db.current != nil {
		to := TimeFromStd(now)
		db.current.To = &to
		db.current = nil
	} else {
		return ErrNotRunning
	}
	return nil
}

func (db *InMemDb) SaveEntry(entry *Entry) (*Entry, error) {
	if entry.Id < 0 || entry.Id >= len(db.entries) {
		copyTask := *entry
		copyTask.Id = len(db.entries)
		db.entries = append(db.entries, &copyTask)

		return &copyTask, nil
	}

	existent := db.entries[entry.Id]
	existent.Comment = entry.Comment
	existent.Tag = entry.Tag
	existent.From = entry.From
	existent.To = entry.To
	existent.Date = entry.Date
	return existent, nil
}

func (db *InMemDb) GetTasks() ([]*Task, error) {
	res := make([]*Task, 0, len(db.tasks))
	for _, task := range db.tasks {
		res = append(res, task)
	}

	return res, nil
}

func (db *InMemDb) QueryTask(id *int, group *string, ident *string) ([]*Task, error) {
	res := make([]*Task, 0, 1)
	for _, task := range db.tasks {
		if id != nil && task.Id != *id {
			continue
		}
		if group != nil && task.Group != group {
			continue
		}
		if ident != nil && task.Ident != ident {
			continue
		}
		res = append(res, task)
	}

	return res, nil
}
func (db *InMemDb) SaveTask(task *Task) (newTask *Task, err error) {
	var tasks []*Task

	tasks, err = db.QueryTask(&task.Id, nil, nil)
	if err != nil {
		return
	}
	if len(tasks) > 0 {
		newTask = tasks[0]
		newTask.Text = task.Text
		newTask.Group = task.Group
		newTask.Ident = task.Ident
	} else {
		taskCopy := *task
		taskCopy.Id = len(db.tasks)
		db.tasks = append(db.tasks, &taskCopy)
		newTask = &taskCopy
	}

	return
}