package git

import (
	"context"
	"strings"
)

// HasChanges reports whether the working tree at workspaceRoot has any
// uncommitted changes (staged, unstaged, or untracked).
func HasChanges(ctx context.Context, workspaceRoot string) (bool, error) {
	out, _, err := runGit(ctx, workspaceRoot, "status", "--porcelain")
	if err != nil {
		return false, err
	}
	return strings.TrimSpace(out) != "", nil
}

// MergePreviewOpts carries options for MergePreview.
type MergePreviewOpts struct {
	WorkspaceRoot string
	Branch        string // branch to preview-merge into HEAD
}

// MergePreviewResult holds the outcome of a preview merge attempt.
// When Clean is false, Conflicts lists the raw CONFLICT lines from git output.
// Faithful to the TS implementation: the repo is left in merge-in-progress
// state so the caller can inspect it; run `git merge --abort` to undo.
type MergePreviewResult struct {
	Clean     bool
	Conflicts []string
	Output    string
}

// MergePreview runs git merge --no-commit --no-ff <Branch> in WorkspaceRoot.
// On success (no conflicts) Clean is true. On conflict, Clean is false and
// Conflicts lists the CONFLICT lines from git output.
func MergePreview(ctx context.Context, opts MergePreviewOpts) (MergePreviewResult, error) {
	stdout, stderr, err := runGit(ctx, opts.WorkspaceRoot, "merge", "--no-commit", "--no-ff", opts.Branch)
	combined := strings.TrimSpace(stdout + "\n" + stderr)
	if err == nil {
		return MergePreviewResult{Clean: true, Output: combined}, nil
	}
	var conflicts []string
	for _, line := range strings.Split(combined, "\n") {
		// git outputs "CONFLICT" in English or "冲突" in localized builds.
		if strings.HasPrefix(line, "CONFLICT") || strings.Contains(line, "冲突") {
			conflicts = append(conflicts, line)
		}
	}
	return MergePreviewResult{
		Clean:     false,
		Conflicts: conflicts,
		Output:    combined,
	}, err
}