package gitinfo

import (
	"errors"
	"runtime/debug"
	"time"
)

// GitInfo is the git info for a build
type GitInfo struct {
	Revision string
	Time     time.Time
	Modified bool
}

// MustReadGitInfo returns GitInfo, or dev info when encountering an error
func MustReadGitInfo() *GitInfo {
	info, err := ReadGitInfo()
	if err != nil {
		return &GitInfo{
			Revision: "develop",
			Time:     time.Now(),
			Modified: true,
		}
	}
	return info
}

// ReadGitInfo returns the GitInfo for a build
func ReadGitInfo() (*GitInfo, error) {
	info, ok := readBuildInfo()
	if !ok {
		return nil, ErrNoBuildInfo
	}

	git := &GitInfo{}
	var vcs string
	for _, setting := range info.Settings {
		switch setting.Key {
		case "vcs":
			vcs = setting.Value
		case "vcs.revision":
			git.Revision = setting.Value
		case "vcs.time":
			t, err := time.Parse(time.RFC3339, setting.Value)
			if err != nil {
				return nil, err
			}
			git.Time = t
		case "vcs.modified":
			git.Modified = setting.Value == "true"
		}
	}
	if vcs != "git" {
		return nil, ErrNoGit
	}

	return git, nil
}

var (
	readBuildInfo = debug.ReadBuildInfo

	ErrNoBuildInfo = errors.New("could not read build info")
	ErrNoGit       = errors.New("vcs is not git")
)