package main

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func TestPatchFrontmatterField_UpdateExistingKey(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "0119-x.md")
	original := "---\n" +
		"id: \"0119\"\n" +
		"title: \"Test\"\n" +
		"status: pendiente\n" +
		"priority: alta\n" +
		"tags: [a, b]\n" +
		"---\n" +
		"\n" +
		"# Body heading\n" +
		"\n" +
		"Some body.\n"
	if err := os.WriteFile(path, []byte(original), 0o644); err != nil {
		t.Fatalf("write: %v", err)
	}
	if err := PatchFrontmatterField(path, "status", "en-curso"); err != nil {
		t.Fatalf("patch: %v", err)
	}
	got, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("read: %v", err)
	}
	gotStr := string(got)
	if !strings.Contains(gotStr, "status: en-curso") {
		t.Fatalf("expected status: en-curso, got:\n%s", gotStr)
	}
	// Preserve everything else.
	for _, line := range []string{
		`id: "0119"`,
		`title: "Test"`,
		`priority: alta`,
		`tags: [a, b]`,
		`# Body heading`,
		`Some body.`,
	} {
		if !strings.Contains(gotStr, line) {
			t.Fatalf("line %q lost after patch, got:\n%s", line, gotStr)
		}
	}
	// Ensure original status line is gone (no duplicate).
	if strings.Count(gotStr, "status:") != 1 {
		t.Fatalf("expected exactly one status: line, got %d:\n%s", strings.Count(gotStr, "status:"), gotStr)
	}
}

func TestPatchFrontmatterField_InsertMissingKey(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "0119-x.md")
	original := "---\n" +
		"id: \"0119\"\n" +
		"title: \"Test\"\n" +
		"---\n" +
		"body\n"
	if err := os.WriteFile(path, []byte(original), 0o644); err != nil {
		t.Fatalf("write: %v", err)
	}
	if err := PatchFrontmatterField(path, "status", "done"); err != nil {
		t.Fatalf("patch: %v", err)
	}
	got, _ := os.ReadFile(path)
	gotStr := string(got)
	if !strings.Contains(gotStr, "status: done") {
		t.Fatalf("missing inserted status line:\n%s", gotStr)
	}
	if !strings.Contains(gotStr, "body") {
		t.Fatalf("body lost:\n%s", gotStr)
	}
}

func TestPatchFrontmatterField_NoFrontmatter(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "plain.md")
	_ = os.WriteFile(path, []byte("just a body\n"), 0o644)
	err := PatchFrontmatterField(path, "status", "done")
	if err == nil {
		t.Fatalf("expected error for missing frontmatter")
	}
}

func TestPatchFrontmatterField_AtomicNoLeftovers(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "0119.md")
	_ = os.WriteFile(path, []byte("---\nid: \"0119\"\nstatus: pendiente\n---\n"), 0o644)
	if err := PatchFrontmatterField(path, "status", "en-curso"); err != nil {
		t.Fatalf("patch: %v", err)
	}
	entries, _ := os.ReadDir(dir)
	for _, e := range entries {
		if strings.HasPrefix(e.Name(), ".fm.") || strings.HasSuffix(e.Name(), ".tmp") {
			t.Fatalf("leftover tmp file: %s", e.Name())
		}
	}
}