package lib

import (
	"sort"
	"time"
)

// TotalTime represents the time spent per project and activity including a total summary.
type TotalTime struct {
	Totals   []*TotalTimeEntry
	TotalSum time.Duration
}

// TotalTimeEntry represents the time spent for a project and an activity.
type TotalTimeEntry struct {
	ProjectID  string
	Project    string
	ActivityID string
	Activity   string
	Duration   time.Duration
}

// GetTimeTotals collects the time spent per project and activity for a time range.
func GetTimeTotals(start, end time.Time) (TotalTime, error) {
	totalTime := TotalTime{
		Totals: []*TotalTimeEntry{},
	}

	entries, entriesErr := readTimeRange(start, end)
	if entriesErr != nil {
		return totalTime, entriesErr
	}
	if len(entries) == 0 {
		return totalTime, nil
	}

	totalsMap := make(map[string]map[string]time.Duration)
	for _, entry := range entries {
		project, projectFound := totalsMap[entry.ProjectID]
		if !projectFound {
			project = make(map[string]time.Duration)
			totalsMap[entry.ProjectID] = project
		}

		activity := project[entry.ActivityID]
		project[entry.ActivityID] = activity + entry.End.Sub(entry.Start)
	}
	if len(totalsMap) == 0 {
		return totalTime, nil
	}

	for projectID, activities := range totalsMap {
		for activity, duration := range activities {
			totalEntry := TotalTimeEntry{
				ProjectID:  projectID,
				ActivityID: activity,
				Duration:   duration,
			}
			totalTime.Totals = append(totalTime.Totals, &totalEntry)
			totalTime.TotalSum = totalTime.TotalSum + duration
		}
	}

	return totalTime, nil
}

// GetTimeSummary gathers time entries for a given day. The entries are sorted by start time ascending.
func GetTimeSummary() ([]*Time, error) {
	dayStart := time.Now().Truncate(24 * time.Hour)
	dayEnd := time.Now().Truncate(24*time.Hour).AddDate(0, 0, 1).Add(-1 * time.Second)
	entries, entriesErr := readTimeRange(dayStart, dayEnd)
	if entriesErr != nil {
		return nil, entriesErr
	}

	sort.Slice(entries, func(i, j int) bool {
		return entries[i].Start.Before(entries[j].Start)
	})

	return entries, nil
}