// Fenrir console screen reader.
// Copyright (c) 2026 Storm Dragon
// SPDX-License-Identifier: GPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
// more details.
//
// You should have received a copy of the GNU General Public License along with
// this program. If not, see <https://www.gnu.org/licenses/gpl-3.0.html>.

package reader

import (
	"bytes"
	"encoding/json"
	"log/slog"
	"reflect"
	"strings"
	"testing"

	"git.stormux.org/storm/fenrir/internal/command"
	"git.stormux.org/storm/fenrir/internal/presentation"
	"git.stormux.org/storm/fenrir/internal/screen"
)

func capture_diagnostics(t *testing.T, level slog.Leveler) *bytes.Buffer {
	t.Helper()
	var log bytes.Buffer
	previousLogger := slog.Default()
	slog.SetDefault(slog.New(slog.NewJSONHandler(&log, &slog.HandlerOptions{Level: level})))
	t.Cleanup(func() { slog.SetDefault(previousLogger) })
	return &log
}

func check_update_record(t *testing.T, log *bytes.Buffer, fields map[string]string) map[string]json.RawMessage {
	t.Helper()
	lines := bytes.Split(bytes.TrimSpace(log.Bytes()), []byte("\n"))
	var record map[string]json.RawMessage
	if err := json.Unmarshal(lines[len(lines)-1], &record); err != nil {
		t.Fatal(err, log.String())
	}
	fields["msg"] = `"reader update"`
	for field, want := range fields {
		if got := string(record[field]); got != want {
			t.Errorf("%s=%s, want %s", field, got, want)
		}
	}
	if strings.Contains(log.String(), "PRIVATE") {
		t.Fatal("diagnostics exposed screen or output text")
	}
	return record
}

func TestReaderDiagnosticsCursorAndStatusWithoutText(t *testing.T) {
	var level slog.LevelVar
	level.Set(slog.LevelDebug)
	log := capture_diagnostics(t, &level)
	r := New()
	r.Update(fixture("PRIVATE first", "PRIVATE second", "1/2 PRIVATE"))
	r.Command(command.CurrentLine)
	r.Command(command.NextLine)
	log.Reset()
	next := fixture("PRIVATE first", "PRIVATE second", "2/2 PRIVATE")
	next.Y = 1
	r.Note_input(true, false, false)
	want := []presentation.Message{presentation.Character_message('2'), {Text: "PRIVATE second"}}
	if got := r.Update(next); !reflect.DeepEqual(got, want) {
		t.Fatal("diagnostics changed cursor feedback", got)
	}
	check_update_record(t, log, map[string]string{
		"cursor": "[0,1]", "previous_cursor": "[0,0]", "mode": `"cursor"`,
		"text_rows": "[2]", "text_cells": "1", "messages": "2", "message_lengths": "[1,14]",
		"path": `"screen-changes"`, "review": "false", "cursor_echo": "true",
	})
	log.Reset()
	level.Set(slog.LevelInfo)
	r.Update(next)
	if log.Len() != 0 {
		t.Fatal("reader diagnostics were not opt-in", log.String())
	}
}

func TestReaderDiagnosticsStationaryCursorAndSuppression(t *testing.T) {
	for _, testCase := range []struct {
		name, mode, path  string
		review, automatic bool
		messages          string
	}{
		{"cursor", "cursor", "screen-changes", false, true, "0"},
		{"highlight", "highlight", "highlight", false, true, "1"},
		{"review", "cursor", "screen-changes", true, true, "0"},
		{"automatic off", "cursor", "automatic-disabled", false, false, "0"},
	} {
		t.Run(testCase.name, func(t *testing.T) {
			log := capture_diagnostics(t, slog.LevelDebug)
			before := fixture("PRIVATE first", "PRIVATE second", "third", "status")
			before.Attributes = make([]screen.Attribute, len(before.Cells))
			next := before
			next.Attributes = make([]screen.Attribute, len(before.Cells))
			selected := screen.Attribute{Foreground: 7, Background: 4}
			for col := range before.Cols {
				before.Attributes[col] = selected
				next.Attributes[next.Cols+col] = selected
			}
			r := New()
			r.Configure(testCase.automatic, true)
			r.Configure_tracking(testCase.mode)
			r.Update(before)
			if testCase.review {
				r.Command(command.CurrentLine)
			}
			log.Reset()
			r.Update(next)
			check_update_record(t, log, map[string]string{
				"cursor": "[0,0]", "previous_cursor": "[0,0]", "text_rows": "[]",
				"attribute_rows": "[0,1]", "attribute_cells": "40", "attributes": "true",
				"path": `"` + testCase.path + `"`, "messages": testCase.messages,
				"review": map[bool]string{true: "true", false: "false"}[testCase.review],
			})
		})
	}
}

func TestReaderDiagnosticsBoundAttributeDetailsAndHandleSessionChanges(t *testing.T) {
	log := capture_diagnostics(t, slog.LevelDebug)
	r := New()
	r.Update(screen.Snapshot{}) // Inactive captures may have no geometry or cells.
	check_update_record(t, log, map[string]string{"path": `"inactive"`, "comparable": "false"})
	before := fixture("PRIVATE", "PRIVATE", "PRIVATE", "PRIVATE")
	before.Attributes = make([]screen.Attribute, len(before.Cells))
	r.Update(before)
	check_update_record(t, log, map[string]string{"path": `"session-change"`, "comparable": "false"})
	next := before
	next.Attributes = make([]screen.Attribute, len(before.Cells))
	for index := range next.Attributes {
		next.Attributes[index].Background = uint32(index%2 + 1)
	}
	log.Reset()
	r.Update(next)
	record := check_update_record(t, log, map[string]string{
		"attribute_changes_truncated": "true", "attribute_cells": "80", "attribute_rows": "[0,1,2,3]",
	})
	var changes []AttributeChange
	if err := json.Unmarshal(record["attribute_changes"], &changes); err != nil {
		t.Fatal(err)
	}
	if len(changes) != 32 || changes[0].Row != 0 || changes[0].Start != 0 || changes[0].End != 1 || changes[0].After.Background != 1 {
		t.Fatal("attribute details lost geometry/appearance or exceeded their bound", changes)
	}
}