/**
 * The view. It holds no live objects: no harness, lane, session, or model runtime.
 *
 * Everything it renders comes from a replicated `SessionView` snapshot, and everything it does is a
 * command that answers with data. Whether that view is in-process or a socket away is invisible here.
 */

import type { AgentMessage, Entry, LaneSnapshot } from "@earendil-works/pi-agent-core";
import type { AssistantMessage, AuthEvent } from "@earendil-works/pi-ai";
import {
	type Component,
	Container,
	type Focusable,
	fuzzyFilter,
	getKeybindings,
	Input,
	ProcessTerminal,
	ScrollView,
	type SelectItem,
	SelectList,
	type SelectListTheme,
	Spacer,
	setKeybindings,
	Text,
	TruncatedText,
	TuiAltScreen,
	VStack,
} from "@earendil-works/pi-tui";
import { getAgentDir } from "../../../config.ts";
import { KeybindingsManager } from "../../../core/keybindings.ts";
import { createAllToolRenderers } from "../../../core/tools/renderers/index.ts";
import { AssistantMessageComponent } from "../../../modes/interactive/components/assistant-message.ts";
import { CustomEditor } from "../../../modes/interactive/components/custom-editor.ts";
import { DynamicBorder } from "../../../modes/interactive/components/dynamic-border.ts";
import { ExtensionSelectorComponent } from "../../../modes/interactive/components/extension-selector.ts";
import { keyText } from "../../../modes/interactive/components/keybinding-hints.ts";
import { LoginDialogComponent } from "../../../modes/interactive/components/login-dialog.ts";
import {
	type AuthSelectorProvider,
	OAuthSelectorComponent,
} from "../../../modes/interactive/components/oauth-selector.ts";
import {
	type StatusIndicator,
	WorkingStatusIndicator,
} from "../../../modes/interactive/components/status-indicator.ts";
import { ToolExecutionComponent, type ToolRenderers } from "../../../modes/interactive/components/tool-execution.ts";
import { UserMessageComponent } from "../../../modes/interactive/components/user-message.ts";
import { getEditorTheme, initTheme, theme } from "../../../modes/interactive/theme/theme.ts";
import type { AuthPromptRequest, CommandResult, ProviderAccount } from "../shared/protocol.ts";
import type { AttachedSession } from "./session.ts";

const SUBSCRIPTION_LOGIN_LABEL = "Sign in with an account";
const API_KEY_LOGIN_LABEL = "Sign in with an API key";

function userMessageText(message: AgentMessage): string {
	if (message.role !== "user") return "";
	if (typeof message.content === "string") return message.content;
	return message.content
		.filter((content) => content.type === "text")
		.map((content) => content.text)
		.join("");
}

const SELECT_THEME: SelectListTheme = {
	selectedPrefix: (text) => theme.fg("accent", text),
	selectedText: (text) => theme.fg("accent", text),
	description: (text) => theme.fg("muted", text),
	scrollInfo: (text) => theme.fg("dim", text),
	noMatch: (text) => theme.fg("warning", text),
};

/** Fuzzy-searchable list over plain data, used where interactive mode needs a live ModelRuntime. */
class ListSelector extends Container implements Focusable {
	readonly #input = new Input();
	readonly #listContainer = new Container();
	readonly #items: SelectItem[];
	readonly #onSelect: (value: string) => void;
	readonly #onCancel: () => void;
	#list: SelectList;
	#isFocused = false;

	constructor(title: string, items: SelectItem[], onSelect: (value: string) => void, onCancel: () => void) {
		super();
		this.#items = items;
		this.#onSelect = onSelect;
		this.#onCancel = onCancel;
		this.#list = this.#build(items);
		this.addChild(new DynamicBorder());
		this.addChild(new Spacer(1));
		this.addChild(new Text(theme.fg("accent", theme.bold(title)), 1, 0));
		this.addChild(this.#input);
		this.addChild(new Spacer(1));
		this.addChild(this.#listContainer);
		this.addChild(new DynamicBorder());
	}

	get focused(): boolean {
		return this.#isFocused;
	}

	set focused(value: boolean) {
		this.#isFocused = value;
		this.#input.focused = value;
	}

	handleInput(data: string): void {
		const keybindings = getKeybindings();
		const forwarded = ["tui.select.up", "tui.select.down", "tui.select.confirm", "tui.select.cancel"] as const;
		if (forwarded.some((action) => keybindings.matches(data, action))) {
			this.#list.handleInput(data);
			return;
		}
		this.#input.handleInput(data);
		const query = this.#input.getValue();
		const filtered =
			query.length === 0 ? this.#items : fuzzyFilter(this.#items, query, (item) => `${item.label} ${item.value}`);
		this.#list = this.#build(filtered);
	}

	#build(items: SelectItem[]): SelectList {
		const list = new SelectList(items, 10, SELECT_THEME);
		list.onSelect = (item) => this.#onSelect(item.value);
		list.onCancel = () => this.#onCancel();
		this.#listContainer.clear();
		this.#listContainer.addChild(list);
		return list;
	}
}

interface MiniTuiHandlers {
	submit(text: string): void;
	/** Queue the current editor text as a follow-up instead of steering the active run. */
	queueFollowUp(text: string): void;
	interrupt(): void;
	exit(): void;
	selectModel(): void;
}

/** Alt-screen chat surface. Rendering is a function of the replicated snapshot. */
class MiniTui {
	readonly #ui: TuiAltScreen;
	readonly #chat = new Container();
	readonly #queue = new Container();
	readonly #status = new Container();
	readonly #footer = new Text("", 1, 0);
	readonly #editorContainer = new Container();
	readonly #editor: CustomEditor;
	readonly #cwd: string;
	readonly #tools = new Map<string, ToolExecutionComponent>();
	/** Entry ids already painted, in transcript order, so re-renders only append. */
	#renderedEntryIds: string[] = [];
	#streaming: AssistantMessageComponent | undefined;
	#indicator: StatusIndicator | undefined;
	#working = false;
	#mountedDispose: (() => void) | undefined;

	constructor(cwd: string, handlers: MiniTuiHandlers) {
		this.#cwd = cwd;
		this.#ui = new TuiAltScreen(new ProcessTerminal(), false, getAgentDir());
		const keybindings = KeybindingsManager.create();
		setKeybindings(keybindings);
		this.#editor = new CustomEditor(this.#ui, getEditorTheme(), keybindings, { paddingX: 1 });
		this.#editor.onSubmit = handlers.submit;
		this.#editor.onEscape = handlers.interrupt;
		this.#editor.onCtrlD = handlers.exit;
		this.#editor.onAction("app.clear", handlers.exit);
		this.#editor.onAction("app.model.select", handlers.selectModel);
		this.#editor.onAction("app.message.followUp", () => {
			const text = this.#editor.getText().trim();
			if (text.length === 0) return;
			this.#editor.setText("");
			handlers.queueFollowUp(text);
		});

		this.#editorContainer.addChild(this.#editor);
		const transcript = new ScrollView(this.#chat, { follow: "end", primary: true, overscroll: "chain" });
		const dock = new VStack([
			{ component: this.#queue, shrink: 1, minSize: 0 },
			{ component: this.#status, shrink: 1, minSize: 0 },
			{ component: this.#editorContainer, shrink: 1, minSize: 3 },
			{ component: this.#footer, shrink: 1, minSize: 0 },
		]);
		this.#ui.addChild(this.#chat);
		this.#ui.addChild(this.#queue);
		this.#ui.addChild(this.#status);
		this.#ui.addChild(this.#editorContainer);
		this.#ui.addChild(this.#footer);
		this.#ui.setLayoutRoot(
			new VStack([
				{ component: transcript, basis: 0, grow: 1, shrink: 1, minSize: 1 },
				{ component: dock, basis: "auto", grow: 0, shrink: 1, minSize: 1 },
			]),
		);
		this.#ui.setFocus(this.#editor);
	}

	get ui(): TuiAltScreen {
		return this.#ui;
	}

	start(): void {
		this.#ui.start();
	}

	stop(): void {
		this.#mountedDispose?.();
		this.#indicator?.dispose();
		this.#ui.stop();
	}

	render(): void {
		this.#ui.requestRender();
	}

	addText(text: string): void {
		this.#chat.addChild(new Spacer(1));
		this.#chat.addChild(new Text(text, 1, 0));
		this.render();
	}

	setFooter(text: string): void {
		this.#footer.setText(theme.fg("dim", text));
		this.render();
	}

	/** Swap the editor slot for a selector or dialog. */
	mount(component: Component, focus: Component, dispose?: () => void): void {
		this.#mountedDispose?.();
		this.#mountedDispose = dispose;
		this.#editorContainer.clear();
		this.#editorContainer.addChild(component);
		this.#ui.setFocus(focus);
		this.render();
	}

	restoreEditor(): void {
		this.#mountedDispose?.();
		this.#mountedDispose = undefined;
		this.#editorContainer.clear();
		this.#editorContainer.addChild(this.#editor);
		this.#ui.setFocus(this.#editor);
		this.render();
	}

	/**
	 * Paint one replicated snapshot. Settled entries are keyed by id and only appended, so a redraw
	 * per streamed token costs one markdown rebuild, not a full transcript rebuild.
	 */
	apply(snapshot: LaneSnapshot): void {
		this.#syncTranscript(snapshot.transcript);
		this.#syncStreaming(snapshot.operation?.streamingMessage);
		for (const tool of snapshot.operation?.runningTools ?? []) {
			const component = this.#tool(tool.toolName, tool.toolCallId, tool.args);
			if (tool.status === "running") {
				component.markExecutionStarted();
				if (tool.result !== undefined) component.updateResult({ ...tool.result, isError: false }, true);
			} else {
				component.updateResult({ ...tool.result, isError: tool.isError }, false);
			}
		}
		this.#syncQueues(snapshot.queues);
		this.#setWorking(snapshot.operation !== null);
		this.render();
	}

	/** One ordered tagged inbox: steered and queued input, plus writes waiting for a boundary. */
	#syncQueues(queues: LaneSnapshot["queues"]): void {
		this.#queue.clear();
		for (const item of queues) {
			const text =
				item.type === "message" ? userMessageText(item.message).replace(/\s+/g, " ") : `<${item.customType}>`;
			this.#queue.addChild(new TruncatedText(theme.fg("muted", `[${item.kind}] ${text}`), 1, 0));
		}
	}

	#syncTranscript(transcript: readonly Entry[]): void {
		const diverged = this.#renderedEntryIds.some((id, index) => transcript[index]?.id !== id);
		if (diverged) {
			// Compaction, navigation, or a fork rewrote the branch: repaint from scratch.
			this.#chat.clear();
			this.#tools.clear();
			this.#renderedEntryIds = [];
			this.#streaming = undefined;
		}
		for (const entry of transcript.slice(this.#renderedEntryIds.length)) {
			this.#addEntry(entry);
			this.#renderedEntryIds.push(entry.id);
		}
	}

	#addEntry(entry: Entry): void {
		if (entry.type === "compaction") {
			// The compaction entry heads the branch, so it has to render its own retained messages.
			this.addText(theme.fg("muted", `[compaction] compacted from ${entry.tokensBefore} tokens`));
			for (const retained of entry.retainedTail) this.#addMessage(retained);
			return;
		}
		if (entry.type === "branch_summary") {
			this.addText(theme.fg("muted", "[branch summary]"));
			this.addText(entry.summary);
			return;
		}
		if (entry.type === "custom") {
			this.addText(theme.fg("muted", `[${entry.customType}]`));
			return;
		}
		this.#addMessage(entry.message);
	}

	#addMessage(message: AgentMessage): void {
		if (message.role === "user") {
			this.#chat.addChild(new Spacer(1));
			this.#chat.addChild(new UserMessageComponent(userMessageText(message)));
		} else if (message.role === "assistant") {
			// Adopt the streaming component so the settled message replaces it instead of duplicating it.
			const component = this.#streaming ?? new AssistantMessageComponent();
			if (!this.#streaming) this.#chat.addChild(component);
			this.#streaming = undefined;
			component.updateContent(message, false);
			for (const content of message.content) {
				if (content.type !== "toolCall") continue;
				this.#tool(content.name, content.id, content.arguments).setArgsComplete();
			}
		} else if (message.role === "toolResult") {
			this.#tool(message.toolName, message.toolCallId).updateResult(message);
		}
	}

	#syncStreaming(message: AssistantMessage | undefined): void {
		if (!message) return;
		if (!this.#streaming) {
			this.#streaming = new AssistantMessageComponent();
			this.#chat.addChild(this.#streaming);
		}
		this.#streaming.updateContent(message, true);
		for (const content of message.content) {
			if (content.type === "toolCall") this.#tool(content.name, content.id, content.arguments);
		}
	}

	/** Built-in renderers, without the tool implementations or their schemas. */
	static readonly #renderers: Record<string, ToolRenderers> = createAllToolRenderers();

	/** Get or create the component for a tool call; omit `args` to look up without overwriting them. */
	#tool(toolName: string, toolCallId: string, args?: unknown): ToolExecutionComponent {
		const existing = this.#tools.get(toolCallId);
		if (existing) {
			if (args !== undefined) existing.updateArgs(args);
			return existing;
		}
		const component = new ToolExecutionComponent(
			toolName,
			toolCallId,
			args ?? {},
			{},
			MiniTui.#renderers[toolName],
			this.#ui,
			this.#cwd,
		);
		this.#chat.addChild(component);
		this.#tools.set(toolCallId, component);
		return component;
	}

	#setWorking(working: boolean): void {
		if (working === this.#working) return;
		this.#working = working;
		this.#indicator?.dispose();
		this.#indicator = undefined;
		this.#status.clear();
		if (working) {
			this.#indicator = new WorkingStatusIndicator(this.#ui, "Working... (esc to abort)");
			this.#status.addChild(this.#indicator);
		}
	}
}

function toAuthSelectorProviders(accounts: readonly ProviderAccount[]): AuthSelectorProvider[] {
	return accounts.map((account) => ({
		id: account.id,
		name: account.name,
		authType: account.authType,
		...(account.configured ? { status: { type: account.authType, source: account.source ?? "configured" } } : {}),
	}));
}

/** The client half of an interactive login, live only while its dialog is mounted. */
interface LoginUi {
	prompt(request: AuthPromptRequest): Promise<string | null>;
	notify(notice: AuthEvent): void;
}

function runLogin(
	view: MiniTui,
	client: AttachedSession,
	account: ProviderAccount,
	setUi: (ui: LoginUi | undefined) => void,
): Promise<CommandResult> {
	const dialog = new LoginDialogComponent(view.ui, account.id, () => view.restoreEditor(), account.name);
	view.mount(dialog, dialog);
	if (!account.interactive) {
		dialog.showInfo(`${account.methodName ?? "Authentication"} is configured outside pi.`, [], true);
		return Promise.resolve({ ok: true });
	}
	setUi({
		notify: (notice) => {
			if (notice.type === "auth_url") dialog.showAuth(notice.url, notice.instructions);
			else if (notice.type === "device_code") {
				dialog.showDeviceCode(notice);
				dialog.showWaiting("Waiting for authentication...");
			} else if (notice.type === "info") dialog.showInfo(notice.message, notice.links);
			else dialog.showProgress(notice.message);
		},
		prompt: (request) => {
			if (request.type === "manual_code") return dialog.showManualInput(request.message);
			if (request.type !== "select") return dialog.showPrompt(request.message, request.placeholder);
			return new Promise<string | null>((resolve) => {
				const selector = new ExtensionSelectorComponent(
					request.message,
					request.options.map((option) => option.label),
					(label) => {
						view.mount(dialog, dialog);
						resolve(request.options.find((option) => option.label === label)?.id ?? null);
					},
					() => {
						view.mount(dialog, dialog);
						resolve(null);
					},
				);
				view.mount(selector, selector);
			});
		},
	});
	return client.models.login(account.id, account.authType).finally(() => {
		setUi(undefined);
		view.restoreEditor();
	});
}

/** Run the view against one attached session until the user exits. */
export async function runView(client: AttachedSession): Promise<void> {
	initTheme();
	let exit = (): void => {};
	const exited = new Promise<void>((resolve) => {
		exit = () => resolve();
	});

	let view!: MiniTui;
	let loginUi: LoginUi | undefined;
	const report = (result: CommandResult): void => {
		if (!result.ok) view.addText(theme.fg("error", result.error));
	};
	client.onAuth((event) => {
		if (event.type === "notice") {
			loginUi?.notify(event.notice);
			return;
		}
		const answer = loginUi?.prompt(event.request) ?? Promise.resolve(null);
		void answer.then(
			(value) => client.models.authReply(event.requestId, value),
			() => client.models.authReply(event.requestId, null),
		);
	});

	const selectModel = (): void => {
		const items: SelectItem[] = client.state().models.models.map((model) => ({
			value: `${model.provider}/${model.modelId}`,
			label: model.modelId,
			description: model.provider,
		}));
		const selector = new ListSelector(
			"Select model:",
			items,
			(value) => {
				view.restoreEditor();
				const separator = value.indexOf("/");
				void client.lane
					.setModel({ provider: value.slice(0, separator), modelId: value.slice(separator + 1) })
					.then(report);
			},
			() => view.restoreEditor(),
		);
		view.mount(selector, selector);
	};
	const selectLoginProvider = (authType: ProviderAccount["authType"]): void => {
		const accounts = client.state().models.accounts.filter((account) => account.authType === authType);
		if (accounts.length === 0) {
			view.restoreEditor();
			view.addText(theme.fg("dim", "No providers for that method."));
			return;
		}
		const selector = new OAuthSelectorComponent(
			"login",
			toAuthSelectorProviders(accounts),
			(providerId) => {
				view.restoreEditor();
				const account = accounts.find((candidate) => candidate.id === providerId);
				const setLoginUi = (ui: LoginUi | undefined): void => {
					loginUi = ui;
				};
				if (account) void runLogin(view, client, account, setLoginUi).then(report);
			},
			// Cancelling the provider list steps back to the auth method choice, as in interactive mode.
			() => login(),
		);
		view.mount(selector, selector);
	};
	const login = (): void => {
		const selector = new ExtensionSelectorComponent(
			"Select authentication method:",
			[SUBSCRIPTION_LOGIN_LABEL, API_KEY_LOGIN_LABEL],
			(option) => selectLoginProvider(option === SUBSCRIPTION_LOGIN_LABEL ? "oauth" : "api_key"),
			() => view.restoreEditor(),
		);
		view.mount(selector, selector);
	};

	view = new MiniTui(client.state().cwd, {
		submit: (text) => {
			const trimmed = text.trim();
			if (trimmed.length === 0) return;
			if (trimmed === "/model") return selectModel();
			if (trimmed === "/login") return login();
			if (trimmed === "/compact") {
				void client.lane.compact().then(report);
				return;
			}
			// A submission during an active run steers it; alt+enter queues a follow-up instead.
			const busy = client.state().lane.operation !== null;
			void (busy ? client.lane.steer(trimmed) : client.lane.prompt(trimmed)).then(report);
		},
		queueFollowUp: (text) => void client.lane.followUp(text).then(report),
		// The worker is authoritative. Never suppress abort from a potentially stale presentation snapshot.
		interrupt: () => void client.lane.abort().then(report),
		exit,
		selectModel: () => selectModel(),
	});

	const render = (): void => {
		const snapshot = client.state();
		view.apply(snapshot.lane);
		const { model, thinkingLevel } = snapshot.lane.configuration;
		view.setFooter(
			`${model.provider}/${model.modelId} · thinking:${thinkingLevel} · ${keyText("app.model.select")} or /model · /login · /compact · ${keyText("app.message.followUp")} follow-up · ${keyText("app.clear")} exit`,
		);
	};
	const unsubscribe = client.subscribe(render);

	view.start();
	render();
	view.addText(theme.fg("dim", client.state().sessionPath));
	await exited;
	unsubscribe();
	view.stop();
}