package main

import (
	"log"
	"net/http"
	"os"
	"path/filepath"
	"slices"
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
)

func TestOwnerTalksToTheAgentThroughTelegram(t *testing.T) {
	server := newFakeResponses(t)
	server.reply = func(w http.ResponseWriter, call fakeCall) {
		writeEvents(w, completedEvent([]any{messageItem("Hello from the agent.")}, 100, 0, 5))
	}

	telegram := newFakeBot(t)
	bot, _ := startTestBot(t, telegram)
	socket := startTestDaemonWithBot(t, server, bot)
	terminal := startTestClient(t, socket)
	terminal.WaitFor(t, "[connected to OneChat]")

	telegram.Add(botUpdate{
		UpdateID: 1,
		Message:  ownerMessage("hi from the phone"),
	})

	terminal.WaitFor(t, "[telegram] hi from the phone\n[working]\nHello from the agent.\n[done]")
	waitForSent(t, telegram, "Hello from the agent.")
	require.True(t, slices.ContainsFunc(telegram.Calls(), func(call fakeBotCall) bool {
		return call.method == "sendChatAction" && call.params["action"] == "typing"
	}))

	terminal.Type("hi from the desk")
	require.Equal(t, []string{"Hello from the agent.", "[terminal] hi from the desk", "Hello from the agent."}, waitForSent(t, telegram, "Hello from the agent.", "[terminal] hi from the desk", "Hello from the agent."))
}

func TestBotIgnoresEveryoneButTheOwner(t *testing.T) {
	telegram := newFakeBot(t)
	bot, logs := startTestBot(t, telegram)
	socket := startTestDaemonWithBot(t, newFakeResponses(t), bot)
	terminal := startTestClient(t, socket)
	terminal.WaitFor(t, "[connected to OneChat]")

	group := ownerMessage("secret in a group")
	group.Chat = botChat{
		ID:   -100,
		Type: "group",
	}

	stranger := ownerMessage("secret of a stranger")
	stranger.Chat.ID = 77
	stranger.From.ID = 77

	unsigned := ownerMessage("secret with no sender")
	unsigned.From = nil

	for id, message := range []*botMessage{group, stranger, unsigned, nil} {
		telegram.Add(botUpdate{
			UpdateID: int64(10 + id),
			Message:  message,
		})
	}

	require.Eventually(t, func() bool {
		offset, err := loadOffset(bot.offsetPath)
		return err == nil && offset == 14
	}, 10*time.Second, time.Millisecond)

	require.Empty(t, telegram.Sent())
	require.NotContains(t, terminal.Output(), "secret")
	require.NotContains(t, logs.String(), "secret")
	require.Contains(t, logs.String(), "update ignored")
}

func TestBotAnswersThatOnlyTextIsSupported(t *testing.T) {
	telegram := newFakeBot(t)
	bot, _ := startTestBot(t, telegram)
	startTestDaemonWithBot(t, newFakeResponses(t), bot)

	telegram.Add(botUpdate{
		UpdateID: 1,
		Message:  ownerMessage(""),
	})

	waitForSent(t, telegram, textOnly)
}

func TestStopFromTelegramInterruptsTheTurn(t *testing.T) {
	server := newFakeResponses(t)
	arrived := make(chan struct{})
	release := make(chan struct{})
	t.Cleanup(func() {
		close(release)
	})

	server.reply = func(w http.ResponseWriter, call fakeCall) {
		close(arrived)
		<-release
	}

	telegram := newFakeBot(t)
	bot, _ := startTestBot(t, telegram)
	startTestDaemonWithBot(t, server, bot)

	telegram.Add(botUpdate{
		UpdateID: 1,
		Message:  ownerMessage("a long task"),
	})

	<-arrived
	telegram.Add(botUpdate{
		UpdateID: 2,
		Message:  ownerMessage(stopCommand),
	})

	waitForSent(t, telegram, "Error: interrupted")

	telegram.Add(botUpdate{
		UpdateID: 3,
		Message:  ownerMessage(stopCommand),
	})

	waitForSent(t, telegram, "Error: interrupted", "No turn runs.")
}

func TestBotStartsAtTheStoredOffset(t *testing.T) {
	server := newFakeResponses(t)
	server.reply = func(w http.ResponseWriter, call fakeCall) {
		writeEvents(w, completedEvent([]any{messageItem("ok")}, 100, 0, 5))
	}

	telegram := newFakeBot(t)
	bot, _ := startTestBot(t, telegram)
	require.NoError(t, saveOffset(bot.offsetPath, 10))

	telegram.Add(botUpdate{
		UpdateID: 9,
		Message:  ownerMessage("handled before the restart"),
	})

	telegram.Add(botUpdate{
		UpdateID: 10,
		Message:  ownerMessage("new after the restart"),
	})

	socket := startTestDaemonWithBot(t, server, bot)
	terminal := startTestClient(t, socket)
	terminal.WaitFor(t, "[connected to OneChat]")
	waitForSent(t, telegram, "ok")

	require.Equal(t, float64(10), telegram.Calls()[0].params["offset"])
	require.NotContains(t, terminal.Output(), "handled before the restart")

	require.Eventually(t, func() bool {
		offset, err := loadOffset(bot.offsetPath)
		return err == nil && offset == 11
	}, 10*time.Second, time.Millisecond)
}

func TestBotTriesAgainAfterFailures(t *testing.T) {
	server := newFakeResponses(t)
	server.reply = func(w http.ResponseWriter, call fakeCall) {
		writeEvents(w, completedEvent([]any{messageItem("ok")}, 100, 0, 5))
	}

	telegram := newFakeBot(t)
	failures := map[string]int{
		"getUpdates":  2,
		"sendMessage": 1,
	}

	telegram.fail = func(call fakeBotCall) (int, string) {
		if failures[call.method] == 0 {
			return 0, ""
		}

		failures[call.method]--
		if call.method == "sendMessage" {
			return http.StatusTooManyRequests, "Too Many Requests: retry after 1"
		}

		return http.StatusBadGateway, "Bad Gateway"
	}

	bot, logs := startTestBot(t, telegram)
	startTestDaemonWithBot(t, server, bot)

	telegram.Add(botUpdate{
		UpdateID: 1,
		Message:  ownerMessage("hello"),
	})

	waitForSent(t, telegram, "ok")
	require.Contains(t, logs.String(), "answered 502")
	require.Contains(t, logs.String(), "answered 429")
	require.NotContains(t, logs.String(), testBotToken)
}

func TestDeliverTriesAgainAfterATimeout(t *testing.T) {
	telegram := newFakeBot(t)
	stalls := 1
	telegram.stall = func(call fakeBotCall) bool {
		if call.method != "sendMessage" || stalls == 0 {
			return false
		}

		stalls--

		return true
	}

	bot, logs := startTestBot(t, telegram)
	bot.api.sendTimeout = 50 * time.Millisecond
	bot.deliver(t.Context(), botPart{
		text: "hello",
	})

	require.Equal(t, []string{"hello"}, telegram.Sent())
	require.Len(t, telegram.Calls(), 2)
	require.Contains(t, logs.String(), "no valid answer")
	require.NotContains(t, logs.String(), testBotToken)
}

func TestOnlyRepliesGetEntities(t *testing.T) {
	server := newFakeResponses(t)
	server.reply = func(w http.ResponseWriter, call fakeCall) {
		writeEvents(w, completedEvent([]any{messageItem("**Done** with `x`.")}, 100, 0, 5))
	}

	telegram := newFakeBot(t)
	bot, _ := startTestBot(t, telegram)
	socket := startTestDaemonWithBot(t, server, bot)
	terminal := startTestClient(t, socket)
	terminal.WaitFor(t, "[connected to OneChat]")

	terminal.Type("make **it** so")
	waitForSent(t, telegram, "[terminal] make **it** so", "Done with x.")

	telegram.Add(botUpdate{
		UpdateID: 1,
		Message:  ownerMessage(""),
	})

	waitForSent(t, telegram, textOnly)

	entities := map[string]any{}
	for _, call := range telegram.Calls() {
		if call.method == "sendMessage" {
			entities[call.params["text"].(string)] = call.params["entities"]
		}
	}

	require.Equal(t, map[string]any{
		"[terminal] make **it** so": nil,
		"Done with x.": []any{
			map[string]any{
				"type":   "bold",
				"offset": float64(0),
				"length": float64(4),
			},
			map[string]any{
				"type":   "code",
				"offset": float64(10),
				"length": float64(1),
			},
		},
		textOnly: nil,
	}, entities)
}

func TestRefusedEntitiesGoAgainAsPlainText(t *testing.T) {
	telegram := newFakeBot(t)
	telegram.fail = func(call fakeBotCall) (int, string) {
		if call.params["entities"] == nil {
			return 0, ""
		}

		return http.StatusBadRequest, "Bad Request: can't parse entities of bot" + testBotToken
	}

	bot, logs := startTestBot(t, telegram)
	text, entities := markdownEntities("a **secret** word")
	bot.deliver(t.Context(), botPart{
		text:     text,
		entities: entities,
	})

	calls := telegram.Calls()
	require.Len(t, calls, 2)
	require.NotNil(t, calls[0].params["entities"])
	require.Nil(t, calls[1].params["entities"])
	require.Equal(t, []string{"a secret word"}, telegram.Sent())
	require.Equal(t, 1, strings.Count(logs.String(), "\n"))
	require.Contains(t, logs.String(), "entities refused")
	require.NotContains(t, logs.String(), testBotToken)
	require.NotContains(t, logs.String(), "secret word")
}

func TestBotLogsNoTokenWhenTheNetworkFails(t *testing.T) {
	telegram := newFakeBot(t)
	telegram.Close()

	bot, logs := startTestBot(t, telegram)
	startTestDaemonWithBot(t, newFakeResponses(t), bot)

	require.Eventually(t, func() bool {
		return strings.Count(logs.String(), "no valid answer") >= 2
	}, 10*time.Second, time.Millisecond)
	require.NotContains(t, logs.String(), testBotToken)
}

func TestSplitMessage(t *testing.T) {
	testCases := []struct {
		name  string
		text  string
		limit int
		parts []string
	}{
		{
			name:  "short text stays whole",
			text:  "one two",
			limit: 10,
			parts: []string{"one two"},
		},
		{
			name:  "cut after the last line break",
			text:  "first line\nsecond line",
			limit: 16,
			parts: []string{"first line\n", "second line"},
		},
		{
			name:  "cut after the last space without a line break",
			text:  "aaaa bbbb cccc",
			limit: 12,
			parts: []string{"aaaa bbbb ", "cccc"},
		},
		{
			name:  "hard cut of one long word",
			text:  "abcdefghij",
			limit: 4,
			parts: []string{"abcd", "efgh", "ij"},
		},
		{
			name:  "a character outside the BMP counts two units and is not cut",
			text:  "ab\U0001F600cd",
			limit: 3,
			parts: []string{"ab", "\U0001F600c", "d"},
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			require.Equal(t, tc.parts, splitMessage(tc.text, tc.limit))
		})
	}

	long := strings.Repeat("word ", 2000)
	parts := splitMessage(long, messageUnits)
	require.Len(t, parts, 3)
	require.Equal(t, long, strings.Join(parts, ""))
}

func TestSplitEntitiesCutsAnEntityAcrossASplit(t *testing.T) {
	parts := splitEntities("aabbbbcc", []botEntity{
		{
			Type:   "bold",
			Offset: 2,
			Length: 4,
		},
		{
			Type:   "italic",
			Offset: 6,
			Length: 2,
		},
	}, 5)

	require.Equal(t, []botPart{
		{
			text: "aabbb",
			entities: []botEntity{
				{
					Type:   "bold",
					Offset: 2,
					Length: 3,
				},
			},
		},
		{
			text: "bcc",
			entities: []botEntity{
				{
					Type:   "bold",
					Offset: 0,
					Length: 1,
				},
				{
					Type:   "italic",
					Offset: 1,
					Length: 2,
				},
			},
		},
	}, parts)
}

func TestSplitRich(t *testing.T) {
	testCases := []struct {
		name     string
		markdown string
		limit    int
		parts    []string
	}{
		{
			name:     "short reply stays whole",
			markdown: "| a | b |",
			limit:    100,
			parts:    []string{"| a | b |"},
		},
		{
			name:     "cut after a blank line keeps a table whole",
			markdown: "Intro.\n\n| a | b |\n|---|---|\n| 1 | 2 |\n",
			limit:    30,
			parts:    []string{"Intro.\n\n", "| a | b |\n|---|---|\n| 1 | 2 |\n"},
		},
		{
			name:     "blank line in a code block is not a cut",
			markdown: "Text.\n\n```go\nx\n\ny\n```\n\nEnd.\n",
			limit:    20,
			parts:    []string{"Text.\n\n", "```go\nx\n\ny\n```\n\n", "End.\n"},
		},
		{
			name:     "paragraph with no blank line is cut after a line",
			markdown: "aaa\nbbb\nccc\n",
			limit:    9,
			parts:    []string{"aaa\nbbb\n", "ccc\n"},
		},
		{
			name:     "long code block is closed and opened again",
			markdown: "```sh\none\ntwo\nthree\n```\n",
			limit:    16,
			parts:    []string{"```sh\none\n```\n", "```sh\ntwo\n```\n", "```sh\nthree\n```\n"},
		},
		{
			name:     "long line is cut at the limit and not inside a character",
			markdown: "ab\u00e9cd",
			limit:    3,
			parts:    []string{"ab", "\u00e9c", "d"},
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			require.Equal(t, tc.parts, splitRich(tc.markdown, tc.limit))
		})
	}

	long := strings.Repeat("A paragraph of the reply.\n\n", 2000)
	parts := splitRich(long, richMessageBytes)
	require.Len(t, parts, 2)
	require.Len(t, parts[0], richMessageBytes-richMessageBytes%len("A paragraph of the reply.\n\n"))
	require.Equal(t, long, strings.Join(parts, ""))
}

func TestLoadBotConfig(t *testing.T) {
	testCases := []struct {
		name      string
		content   string
		mode      os.FileMode
		errorText string
	}{
		{
			name:    "owner file is read",
			content: `{"token": "` + testBotToken + `", "owner": 4242}`,
			mode:    0o600,
		},
		{
			name:      "file that others can read is refused",
			content:   `{"token": "` + testBotToken + `", "owner": 4242}`,
			mode:      0o640,
			errorText: "mode must be 0600",
		},
		{
			name:      "token with a path character is refused",
			content:   `{"token": "123:abc/../x", "owner": 4242}`,
			mode:      0o600,
			errorText: "form of a bot token",
		},
		{
			name:      "missing owner is refused",
			content:   `{"token": "` + testBotToken + `"}`,
			mode:      0o600,
			errorText: "numeric Telegram user ID",
		},
		{
			name:      "unknown field is refused",
			content:   `{"token": "` + testBotToken + `", "owner": 4242, "chat": 1}`,
			mode:      0o600,
			errorText: "not valid JSON",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			dir := t.TempDir()
			path := filepath.Join(dir, botConfigFileName)
			require.NoError(t, os.WriteFile(path, []byte(tc.content), tc.mode))
			require.NoError(t, os.Chmod(path, tc.mode))

			config, found, err := loadBotConfig(dir)
			if tc.errorText != "" {
				require.ErrorContains(t, err, tc.errorText)
				require.NotContains(t, err.Error(), testBotToken)

				return
			}

			require.NoError(t, err)
			require.True(t, found)
			require.Equal(t, botConfig{
				Token: testBotToken,
				Owner: testOwner,
			}, config)
		})
	}

	_, found, err := loadBotConfig(t.TempDir())
	require.NoError(t, err)
	require.False(t, found)
}

// startTestBot returns a bot of testOwner on server, with its offset file in a
// temporary directory and short waits, and the buffer of its log.
func startTestBot(t *testing.T, server *fakeBot) (*telegramBot, *syncBuffer) {
	t.Helper()

	logs := &syncBuffer{}
	bot := newTelegramBot(newBotAPI(server.URL, testBotToken), testOwner, filepath.Join(t.TempDir(), offsetFileName), log.New(logs, "", 0))
	bot.minWait = time.Millisecond
	bot.maxWait = 10 * time.Millisecond

	return bot, logs
}

// waitForSent waits until the bot sent the texts in order, and returns them.
func waitForSent(t *testing.T, server *fakeBot, texts ...string) []string {
	t.Helper()

	require.Eventually(t, func() bool {
		sent := server.Sent()
		return len(sent) >= len(texts) && slices.Equal(sent[len(sent)-len(texts):], texts)
	}, 10*time.Second, time.Millisecond, "sent so far: %q", server.Sent())

	return server.Sent()
}