calculate_stats.go

package main

import (
	"time"

	"gopkg.in/src-d/go-git.v4"
	"gopkg.in/src-d/go-git.v4/plumbing/object"
)

// func calcOffset returns the amount of days missing
// to fill the last row of stats graph
func calcOffset() int {
	var offset int
	weekday := time.Now().Weekday()

	switch weekday {
		case time.Sunday:
			offset = 7
		case time.Monday:
			offset = 6
		case time.Tuesday:
			offset = 5
		case time.Wednesday:
			offset = 4
		case time.Thursday:
			offset = 3
		case time.Friday:
			offset = 2
		case time.Saturday:
			offset = 1
	}

	return offset
}

// getBeginningOfDay given a time.Time calculates the start time of that day
func getBeginningOfDay(t time.Time) time.Time {
    year, month, day := t.Date()
    startOfDay := time.Date(year, month, day, 0, 0, 0, 0, t.Location())
    return startOfDay
}

// func countDaysSinceDate return how many days have passed since the given date
func countDaysSinceDate(date time.Time) int {
	days := 0
	now := getBeginningOfDay(time.Now())

	for date.Before(now) {
		date = date.Add(time.Hour*24)
		days++
		if days > daysInLastSixMonths {
			return outOfRange
		}
	}

	return days
}

// fillCommits given a repository found in `path`, gets the commits and
// puts them in the `commits` map, returning it when completed
func fillCommits(email string, path string, commits map[int]int) map[int]int {
	// instantiate repo object from path
	repo, err := git.PlainOpen(path)
	if err != nil {
		panic(err)
	}

	// get HEAD reference
	ref, err := repo.Head()
	if err != nil {
		panic(err)
	}

	// get commit history starting from HEAD
	iterator, err := repo.Log(&git.LogOptions{From : ref.Hash()})
	if err != nil {
		panic(err)
	}

	// iterate the commits
	offset := calcOffset()
	err = iterator.ForEach(func(c *object.Commit) error {
		daysAgo := countDaysSinceDate(c.Author.When) + offset
		
		if c.Author.Email != email {
			return nil
		}

		if daysAgo != outOfRange {	
			// outOfRange is a constant which countDaysSinceDate returns
			// when commit is more than six months old
			commits[daysAgo]++
		}

		return nil
	})
	if err != nil {
		panic(err)
	}

	return commits
}

// func processRepositories given a email address, returns 
// commits made in the last six months
func processRepositories(email string) map[int]int {
	file_path := getDotFilePath()
	repos := parseFileLinesToSlice(file_path)
	daysInMap := daysInLastSixMonths	// daysInLastSixMonths is a constant

	commits := make(map[int]int, daysInMap)
	for i := daysInMap; i > 0; i-- {
		commits[i] = 0
	}

	for _, path := range repos {
		commits = fillCommits(email, path, commits)
	}

	return commits
}

// func stats calculates and prints the stats.
func stats(email string){
	commits := processRepositories(email)
	printCommitStats(commits)
}