// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: PolyForm-Noncommercial-1.0.0

package audit

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

func TestDisabledLogWritesNothing(t *testing.T) {
	l := New("")
	if l.Enabled() {
		t.Fatal("Enabled = true for empty path")
	}
	l.Record(Entry{User: "admin", Action: "login"})
}

func TestRecordAppendsJSONLines(t *testing.T) {
	path := filepath.Join(t.TempDir(), "sub", "audit.log")
	l := New(path)
	if !l.Enabled() {
		t.Fatal("Enabled = false for a real path")
	}
	l.Record(Entry{User: "admin", Action: "post.created", Resource: "hello", IP: "127.0.0.1"})
	l.Record(Entry{User: "admin", Action: "post.deleted", Detail: map[string]any{"slug": "hello"}})

	data, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("ReadFile: %v", err)
	}
	lines := strings.Split(strings.TrimSuffix(string(data), "\n"), "\n")
	if len(lines) != 2 {
		t.Fatalf("got %d lines, want 2: %q", len(lines), data)
	}
	var first map[string]any
	if err := json.Unmarshal([]byte(lines[0]), &first); err != nil {
		t.Fatalf("line is not JSON: %v", err)
	}
	if first["user"] != "admin" || first["action"] != "post.created" ||
		first["resource"] != "hello" || first["ip"] != "127.0.0.1" {
		t.Fatalf("first entry = %v", first)
	}
	if _, ok := first["detail"]; ok {
		t.Fatalf("unexpected detail in first entry: %v", first)
	}
	var second map[string]any
	if err := json.Unmarshal([]byte(lines[1]), &second); err != nil {
		t.Fatalf("line is not JSON: %v", err)
	}
	detail, ok := second["detail"].(map[string]any)
	if !ok || detail["slug"] != "hello" {
		t.Fatalf("second entry detail = %v", second)
	}
	ts, _ := first["ts"].(string)
	if len(ts) < 19 || !strings.Contains(ts, "T") {
		t.Fatalf("ts = %q, want ISO timestamp", ts)
	}
}

func TestRecordSurvivesUnwritablePath(t *testing.T) {
	dir := t.TempDir()
	l := New(filepath.Join(dir, "file-as-dir", "x", "audit.log"))
	if err := os.WriteFile(filepath.Join(dir, "file-as-dir"), []byte("x"), 0o600); err != nil {
		t.Fatalf("WriteFile: %v", err)
	}
	l.Record(Entry{User: "admin", Action: "login"}) // must not panic
}

// The handler opens the file once and appends to it, and Close releases
// the handle.
func TestFileIsOpenedOnceAndClosed(t *testing.T) {
	path := filepath.Join(t.TempDir(), "audit.log")
	l := New(path)
	for range 50 {
		l.Record(Entry{User: "admin", Action: "post.updated", Resource: "hello"})
	}
	if err := l.Close(); err != nil {
		t.Fatalf("Close: %v", err)
	}
	data, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("ReadFile: %v", err)
	}
	if got := strings.Count(string(data), "\n"); got != 50 {
		t.Fatalf("lines = %d, want 50", got)
	}
	// A write after Close reopens it rather than losing the line.
	l.Record(Entry{User: "admin", Action: "post.deleted"})
	data, err = os.ReadFile(path)
	if err != nil {
		t.Fatalf("ReadFile: %v", err)
	}
	if got := strings.Count(string(data), "\n"); got != 51 {
		t.Fatalf("lines = %d, want 51", got)
	}
	if err := l.Close(); err != nil {
		t.Fatalf("Close: %v", err)
	}
}

// An unwritable destination is reported once and never fails the caller.
func TestUnwritableDestinationIsNotFatal(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "audit.log")
	if err := os.MkdirAll(path, 0o755); err != nil {
		t.Fatalf("mkdir: %v", err)
	}
	l := New(path)
	l.Record(Entry{User: "admin", Action: "post.created"})
	l.Record(Entry{User: "admin", Action: "post.created"})
	if err := l.Close(); err != nil {
		t.Fatalf("Close: %v", err)
	}
}

// A transient open failure must not silence the log for the life of the
// process: once the obstruction is gone, the next record writes.
func TestRecordRecoversAfterThePathBecomesWritable(t *testing.T) {
	dir := t.TempDir()
	// A regular file where the log's parent directory should be makes
	// MkdirAll fail.
	blocker := filepath.Join(dir, "blocked")
	if err := os.WriteFile(blocker, []byte("x"), 0o644); err != nil {
		t.Fatalf("write blocker: %v", err)
	}
	log := New(filepath.Join(blocker, "sub", "audit.log"))
	log.Record(Entry{User: "u", Action: "first"})
	if err := log.Close(); err != nil {
		t.Fatalf("close: %v", err)
	}
	if err := os.Remove(blocker); err != nil {
		t.Fatalf("remove blocker: %v", err)
	}
	log.Record(Entry{User: "u", Action: "second"})
	if err := log.Close(); err != nil {
		t.Fatalf("close: %v", err)
	}
	raw, err := os.ReadFile(filepath.Join(dir, "blocked", "sub", "audit.log"))
	if err != nil {
		t.Fatalf("the audit log never recovered: %v", err)
	}
	if !strings.Contains(string(raw), `"action":"second"`) {
		t.Fatalf("recovered log = %s", raw)
	}
}