package healthcheck

import (
	"fmt"
	"log/slog"
	"strings"
	"unicode"

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing/object"
)

// nonAsciiMsg checks for non-ASCII characters in the commit message.
// If the message starts with "Merge pull request", it skips the non-ASCII characters check.
// Otherwise, it iterates over each character in the message and checks if it is a non-ASCII character.
// If a non-ASCII character is found, it returns an error indicating not to use non-ASCII characters in commit messages.
// Otherwise, it returns nil indicating that the commit message is valid.
// It skips the non-ASCII characters check for lines starting with specific keywords like "Co-authored-by", "Reviewed-by", and "Co-committed-by".
func NonAsciiMsg(root string) error {
	repo, err := git.PlainOpen(root)
	if err != nil {
		slog.Error("opening git repo", "err", err)
		return fmt.Errorf("error opening git repo: %v", err)
	}

	ref, err := repo.Head()
	if err != nil {
		slog.Error("getting reference", "err", err)
		return fmt.Errorf("error getting reference: %v", err)
	}
	commits, err := repo.Log(&git.LogOptions{From: ref.Hash()})
	if err != nil {
		slog.Error("getting commits", "err", err)
		return fmt.Errorf("error getting commits from reference %s: %v", ref.Hash(), err)
	}

	var msgs []string
	err = commits.ForEach(func(c *object.Commit) error {
		msgs = append(msgs, c.Message)
		return nil
	})
	if err != nil {
		slog.Error("iterating commits", "err", err)
		return fmt.Errorf("error iterating commits: %v", err)
	}

	var nonAsciiMsgs []string
	// List of prefixes to ignore in the commit message
	ignoredPrefixes := []string{
		"Co-authored-by:",
		"Reviewed-by:",
		"Co-committed-by:",
		"Reviewed-on:",
	}

	for _, msg := range msgs {
		if msg == "" {
			continue
		}
		// Split message by lines and ignore specific lines with prefixes
		lines := strings.Split(msg, "\n")
		for _, line := range lines {
			trimmedLine := strings.TrimSpace(line)
			ignore := false
			for _, prefix := range ignoredPrefixes {
				if strings.HasPrefix(trimmedLine, prefix) {
					ignore = true
					break
				}
			}
			if ignore {
				continue
			}
			// Check for non-ASCII characters in the rest of the lines
			for _, c := range line {
				if c > unicode.MaxASCII {
					nonAsciiMsgs = append(nonAsciiMsgs, msg)
					break
				}
			}
		}
	}
	if len(nonAsciiMsgs) > 0 {
		return fmt.Errorf("Non-ASCII characters in commit messages:\n%s", strings.Join(nonAsciiMsgs, "\n"))
	}
	return nil
}