package git

import (
	"bytes"
	"errors"
	"fmt"
	"net/url"
	"os/exec"
	"regexp"
	"strings"

	"github.com/github/gh-cli/utils"
)

func VerifyRef(ref string) bool {
	showRef := exec.Command("git", "show-ref", "--verify", "--quiet", ref)
	err := utils.PrepareCmd(showRef).Run()
	return err == nil
}

func CurrentBranch() (string, error) {
	branchCmd := exec.Command("git", "branch", "--show-current")
	output, err := utils.PrepareCmd(branchCmd).Output()
	branchName := firstLine(output)
	if err == nil && branchName == "" {
		return "", errors.New("git: not on any branch")
	}
	return branchName, err
}

func listRemotes() ([]string, error) {
	remoteCmd := exec.Command("git", "remote", "-v")
	output, err := utils.PrepareCmd(remoteCmd).Output()
	return outputLines(output), err
}

func Config(name string) (string, error) {
	configCmd := exec.Command("git", "config", name)
	output, err := utils.PrepareCmd(configCmd).Output()
	if err != nil {
		return "", fmt.Errorf("unknown config key: %s", name)
	}

	return firstLine(output), nil

}

var GitCommand = func(args ...string) *exec.Cmd {
	return exec.Command("git", args...)
}

func UncommittedChangeCount() (int, error) {
	statusCmd := GitCommand("status", "--porcelain")
	output, err := utils.PrepareCmd(statusCmd).Output()
	if err != nil {
		return 0, err
	}
	lines := strings.Split(string(output), "\n")

	count := 0

	for _, l := range lines {
		if l != "" {
			count++
		}
	}

	return count, nil
}

func Push(remote string, ref string) error {
	pushCmd := GitCommand("push", "--set-upstream", remote, ref)
	return utils.PrepareCmd(pushCmd).Run()
}

type BranchConfig struct {
	RemoteName string
	RemoteURL  *url.URL
	MergeRef   string
}

// ReadBranchConfig parses the `branch.BRANCH.(remote|merge)` part of git config
func ReadBranchConfig(branch string) (cfg BranchConfig) {
	prefix := regexp.QuoteMeta(fmt.Sprintf("branch.%s.", branch))
	configCmd := GitCommand("config", "--get-regexp", fmt.Sprintf("^%s(remote|merge)$", prefix))
	output, err := utils.PrepareCmd(configCmd).Output()
	if err != nil {
		return
	}
	for _, line := range outputLines(output) {
		parts := strings.SplitN(line, " ", 2)
		if len(parts) < 2 {
			continue
		}
		keys := strings.Split(parts[0], ".")
		switch keys[len(keys)-1] {
		case "remote":
			if strings.Contains(parts[1], ":") {
				u, err := ParseURL(parts[1])
				if err != nil {
					continue
				}
				cfg.RemoteURL = u
			} else {
				cfg.RemoteName = parts[1]
			}
		case "merge":
			cfg.MergeRef = parts[1]
		}
	}
	return
}

// ToplevelDir returns the top-level directory path of the current repository
func ToplevelDir() (string, error) {
	showCmd := exec.Command("git", "rev-parse", "--show-toplevel")
	output, err := utils.PrepareCmd(showCmd).Output()
	return firstLine(output), err

}

func outputLines(output []byte) []string {
	lines := strings.TrimSuffix(string(output), "\n")
	return strings.Split(lines, "\n")

}

func firstLine(output []byte) string {
	if i := bytes.IndexAny(output, "\n"); i >= 0 {
		return string(output)[0:i]
	}
	return string(output)
}