import type { ExtensionContext } from "@selesai/code";
import { type EditorComponent, isKeyRelease, Key, matchesKey, truncateToWidth, visibleWidth } from "@earendil-works/pi-tui";
import { formatModelThinking } from "../shared/formatters.ts";
import type { AsyncJobStep, FleetViewPlacement, NestedRunSummary, NestedStepSummary, SubagentState } from "../shared/types.ts";
import { formatWorkflowJsonPreview } from "../workflows/scripted-workflow.ts";

export const FLEET_STATUS_WIDGET_KEY = "subagent-fleet-status";

// Six rows fit the accepted collapsed hierarchy: one owner, four direct leaves, and overflow.
const MAX_AGENT_ROWS = 6;
const REFRESH_MS = 500;

type Theme = ExtensionContext["ui"]["theme"];
type FleetStatusTui = {
	requestRender(): void;
};
type FleetStatusEntry = {
	key: string;
	agent: string;
	modelThinking?: string;
	description?: string;
	startedAt: number;
	tokens: number;
	state: string;
	nestedChildren?: NestedRunSummary[];
};

type FleetNestedRow = {
	name: string;
	state: NestedRunSummary["state"] | NestedStepSummary["status"];
	modelThinking?: string;
	activity?: string;
	startedAt?: number;
	overflow?: number;
};

type FleetTreeRow =
	| { kind: "owner"; entry: FleetStatusEntry }
	| { kind: "nested"; ownerKey: string; row: FleetNestedRow; last: boolean };

export interface FleetStatusOptions {
	refreshMs?: number;
	maxAgentRows?: number;
	placement?: FleetViewPlacement;
}

export function resolveFleetViewPlacement(value: unknown): FleetViewPlacement {
	return value === "aboveEditor" ? "aboveEditor" : "belowEditor";
}

export function formatFleetElapsed(ms: number): string {
	return `${Math.max(0, Math.round(ms / 1000))}s`;
}

export function formatFleetTokens(count: number): string {
	let compact: string;
	if (count >= 1_000_000) compact = `${(count / 1_000_000).toFixed(1)}M`;
	else if (count >= 1_000) compact = `${(count / 1_000).toFixed(1)}k`;
	else compact = `${Math.max(0, Math.round(count))}`;
	return `↓ ${compact} tokens`;
}

function rightAlign(left: string, right: string, width: number): string {
	const rightWidth = visibleWidth(right);
	const maxLeftWidth = Math.max(0, width - rightWidth - 1);
	const leftClamped = truncateToWidth(left, maxLeftWidth);
	const gap = Math.max(1, width - visibleWidth(leftClamped) - rightWidth);
	return truncateToWidth(`${leftClamped}${" ".repeat(gap)}${right}`, width);
}

function isActiveState(value: string): boolean {
	return value === "running" || value === "queued" || value === "pending";
}

function nestedRunLabel(run: NestedRunSummary): string {
	if (run.agent) return run.agent;
	if (run.agents?.length) return run.agents.length === 1 ? run.agents[0]! : `${run.agents.slice(0, 2).join(", ")}${run.agents.length > 2 ? ` +${run.agents.length - 2}` : ""}`;
	return run.id;
}

function nestedActivity(node: NestedRunSummary | NestedStepSummary): string | undefined {
	if (node.currentTool) return `tool ${node.currentTool}`;
	if (node.currentPath) return node.currentPath.split(/[\\/]/).at(-1);
	if (node.activityState === "needs_attention") return "needs attention";
	if (node.activityState === "active_long_running") return "long-running";
	return undefined;
}

function nestedStatusGlyph(state: FleetNestedRow["state"], theme: Theme): string {
	if (state === "running") return theme.fg("accent", "●");
	if (state === "queued" || state === "pending") return theme.fg("muted", "◦");
	if (state === "complete" || state === "completed") return theme.fg("success", "✓");
	if (state === "failed" || state === "rejected") return theme.fg("error", "✗");
	return theme.fg("warning", "■");
}

function nestedFleetRows(children: NestedRunSummary[] | undefined): FleetNestedRow[] {
	const rows: FleetNestedRow[] = [];
	for (const child of children ?? []) {
		const steps = (child.mode === "parallel" || child.mode === "chain") ? child.steps ?? [] : [];
		if (steps.length > 0) {
			for (const step of steps) {
				rows.push({
					name: step.agent,
					state: step.status,
					...(formatModelThinking(step.model, step.thinking) ? { modelThinking: formatModelThinking(step.model, step.thinking) } : {}),
					...(nestedActivity(step) ? { activity: nestedActivity(step) } : {}),
					...(step.startedAt !== undefined ? { startedAt: step.startedAt } : {}),
				});
			}
			continue;
		}
		rows.push({
			name: nestedRunLabel(child),
			state: child.state,
			...(formatModelThinking(child.model, child.thinking) ? { modelThinking: formatModelThinking(child.model, child.thinking) } : {}),
			...(nestedActivity(child) ? { activity: nestedActivity(child) } : {}),
			...(child.startedAt !== undefined ? { startedAt: child.startedAt } : {}),
		});
	}
	const visible = rows.slice(0, 4);
	if (rows.length > visible.length) visible.push({ name: `… +${rows.length - visible.length} more nested leaves`, state: "complete", overflow: rows.length - visible.length });
	return visible;
}

function fleetTreeRows(entries: FleetStatusEntry[]): FleetTreeRow[] {
	const rows: FleetTreeRow[] = [];
	for (const entry of entries) {
		rows.push({ kind: "owner", entry });
		const nested = nestedFleetRows(entry.nestedChildren);
		for (const [index, row] of nested.entries()) rows.push({ kind: "nested", ownerKey: entry.key, row, last: index === nested.length - 1 });
	}
	return rows;
}

function isStaleExtensionContextError(error: unknown): boolean {
	// Pi currently exposes stale contexts as plain Errors without a stable code or subtype.
	return error instanceof Error
		&& (error.message.includes("This extension ctx is stale")
			|| error.message.includes("Extension context no longer active"));
}

export function collectFleetStatusEntries(state: SubagentState): FleetStatusEntry[] {
	const entries: FleetStatusEntry[] = [];
	for (const control of state.foregroundControls.values()) {
		if (control.activeChildren) {
			for (const child of [...control.activeChildren.values()].sort((left, right) => left.index - right.index)) {
				const modelThinking = formatModelThinking(child.model, child.thinking) || undefined;
				entries.push({
					key: `foreground-active:${control.runId}:${child.index}`,
					agent: child.agent,
					...(modelThinking ? { modelThinking } : {}),
					description: child.description,
					startedAt: child.startedAt,
					tokens: child.tokens ?? 0,
					state: "running",
					...((control.nestedChildren?.filter((nested) => nested.parentStepIndex === child.index).length ?? 0) > 0
						? { nestedChildren: control.nestedChildren!.filter((nested) => nested.parentStepIndex === child.index) }
						: control.activeChildren.size === 1 && control.nestedChildren?.length ? { nestedChildren: control.nestedChildren } : {}),
				});
			}
			continue;
		}
		const modelThinking = formatModelThinking(control.model, control.thinking) || undefined;
		entries.push({
			key: `foreground-active:${control.runId}:${control.currentIndex ?? 0}`,
			agent: control.currentAgent ?? control.mode,
			...(modelThinking ? { modelThinking } : {}),
			description: control.description,
			startedAt: control.startedAt,
			tokens: control.tokens ?? 0,
			state: "running",
			...(control.nestedChildren?.length ? { nestedChildren: control.nestedChildren } : {}),
		});
	}

	for (const job of state.asyncJobs.values()) {
		if (!isActiveState(job.status)) continue;
		const startedAt = job.startedAt ?? job.updatedAt ?? Date.now();
		if (job.mode === "workflow") {
			const latestEmit = job.workflow?.emits?.length ? formatWorkflowJsonPreview(job.workflow.emits.at(-1), 120) : undefined;
			entries.push({
				key: `async:${job.asyncId}`,
				agent: "workflow",
				description: latestEmit !== undefined ? `latest emit: ${latestEmit}` : job.description,
				startedAt,
				tokens: job.totalTokens?.total ?? 0,
				state: job.status,
				...(job.nestedChildren?.length ? { nestedChildren: job.nestedChildren } : {}),
			});
			continue;
		}
		const steps: AsyncJobStep[] | undefined = job.steps?.length
			? job.steps
			: job.agents?.map((agent, index) => {
				const pending = job.status === "queued"
					|| (job.mode === "chain" && !job.activeParallelGroup && index !== (job.currentStep ?? 0));
				return { agent, index, status: pending ? "pending" : "running" };
			});
		if (!steps?.length) {
			entries.push({
				key: `async:${job.asyncId}`,
				agent: job.mode ?? "subagent",
				description: job.description,
				startedAt,
				tokens: job.totalTokens?.total ?? 0,
				state: job.status,
				...(job.nestedChildren?.length ? { nestedChildren: job.nestedChildren } : {}),
			});
			continue;
		}
		for (const [offset, step] of steps.entries()) {
			if (!isActiveState(step.status)) continue;
			const index = step.index ?? offset;
			if (step.status === "pending" && job.mode === "chain" && !job.activeParallelGroup && index !== (job.currentStep ?? 0)) continue;
			const modelThinking = formatModelThinking(step.model, step.thinking) || undefined;
			entries.push({
				key: `async:${job.asyncId}:${index}`,
				agent: step.label ? `${step.label} (${step.agent})` : step.agent,
				...(modelThinking ? { modelThinking } : {}),
				description: step.description ?? job.description,
				startedAt: step.startedAt ?? startedAt,
				tokens: step.tokens?.total ?? (steps.length === 1 ? job.totalTokens?.total ?? 0 : 0),
				state: step.status,
				...((step.children?.length ?? 0) > 0
					? { nestedChildren: step.children }
					: job.nestedChildren?.filter((nested) => nested.parentStepIndex === index).length
						? { nestedChildren: job.nestedChildren.filter((nested) => nested.parentStepIndex === index) }
						: {}),
			});
		}
	}

	return entries.sort((left, right) => left.startedAt - right.startedAt || left.key.localeCompare(right.key));
}

export class SubagentFleetStatus {
	private ctx: ExtensionContext | undefined;
	private ui: ExtensionContext["ui"] | undefined;
	private tui: FleetStatusTui | undefined;
	private inputUnsubscribe: (() => void) | undefined;
	private timer: ReturnType<typeof setInterval> | undefined;
	private widgetRegistered = false;
	private active = false;
	private selectedKey = "main";
	private inspectorOpen = false;
	private lastRenderKey = "";
	private entries: FleetStatusEntry[] = [];
	private readonly state: SubagentState;
	private readonly openInspector: (itemKey: string) => Promise<void> | void;
	private readonly refreshMs: number;
	private readonly maxAgentRows: number;
	private readonly placement: FleetViewPlacement;

	constructor(
		state: SubagentState,
		openInspector: (itemKey: string) => Promise<void> | void,
		options: FleetStatusOptions = {},
	) {
		this.state = state;
		this.openInspector = openInspector;
		this.refreshMs = options.refreshMs ?? REFRESH_MS;
		this.maxAgentRows = options.maxAgentRows ?? MAX_AGENT_ROWS;
		this.placement = options.placement ?? "belowEditor";
	}

	setContext(ctx: ExtensionContext): void {
		if (!ctx.hasUI) return;
		const ui = ctx.ui;
		if (this.ui === ui) {
			this.ctx = ctx;
			this.refresh();
			return;
		}
		this.clearUiRegistration();
		this.ctx = ctx;
		this.ui = ui;
		if (typeof ui.onTerminalInput === "function") {
			this.inputUnsubscribe = ui.onTerminalInput((data) => this.handleKey(data));
		}
		this.timer = setInterval(() => this.refresh(), this.refreshMs);
		this.timer.unref?.();
		this.refresh();
	}

	dispose(): void {
		this.clearUiRegistration();
		this.ctx = undefined;
		this.ui = undefined;
		this.entries = [];
		this.active = false;
		this.selectedKey = "main";
		this.inspectorOpen = false;
		this.lastRenderKey = "";
	}

	refresh(): void {
		const ctx = this.getActiveUiContext();
		if (!ctx) return;
		this.entries = collectFleetStatusEntries(this.state);
		this.clampSelection();
		if (this.inspectorOpen || this.state.fleetInspectorOpen) {
			this.lastRenderKey = "";
			if (this.widgetRegistered) {
				ctx.ui.setWidget(FLEET_STATUS_WIDGET_KEY, undefined);
				this.widgetRegistered = false;
				this.tui = undefined;
			}
			return;
		}
		if (this.entries.length === 0) {
			this.active = false;
			this.selectedKey = "main";
			this.lastRenderKey = "";
			if (this.widgetRegistered) {
				ctx.ui.setWidget(FLEET_STATUS_WIDGET_KEY, undefined);
				this.widgetRegistered = false;
				this.tui = undefined;
			}
			return;
		}

		const renderKey = this.getRenderKey();
		if (!this.widgetRegistered) {
			ctx.ui.setWidget(FLEET_STATUS_WIDGET_KEY, (tui, theme) => {
				this.tui = tui;
				return {
					render: (width: number) => this.render(width, theme),
					invalidate: () => {
						this.lastRenderKey = "";
					},
					dispose: () => {
						if (this.tui !== tui) return;
						this.widgetRegistered = false;
						this.tui = undefined;
					},
				};
			}, { placement: this.placement });
			this.widgetRegistered = true;
			this.lastRenderKey = renderKey;
			return;
		}
		if (renderKey === this.lastRenderKey) return;
		this.lastRenderKey = renderKey;
		this.tui?.requestRender();
	}

	handleKey(data: string): { consume?: boolean; data?: string } | undefined {
		const ctx = this.getActiveUiContext();
		if (!ctx || this.entries.length === 0 || isKeyRelease(data)) return undefined;
		if (this.inspectorOpen) return undefined;
		if (!this.editorHasFocus()) {
			if (this.active) this.deactivate();
			return undefined;
		}

		if (!this.active) {
			const activates = matchesKey(data, "down") || matchesKey(data, "left");
			if (!activates || ctx.ui.getEditorText() !== "") return undefined;
			this.active = true;
			this.selectedKey = "main";
			this.refresh();
			return { consume: true };
		}

		const roster = this.rosterKeys();
		const selectedIndex = Math.max(0, roster.indexOf(this.selectedKey));
		if (matchesKey(data, "down") || matchesKey(data, "j")) {
			this.selectedKey = roster[Math.min(roster.length - 1, selectedIndex + 1)] ?? "main";
			this.refresh();
			return { consume: true };
		}
		if (matchesKey(data, "up") || matchesKey(data, "k")) {
			if (selectedIndex === 0) {
				this.deactivate();
				return { consume: true };
			}
			this.selectedKey = roster[selectedIndex - 1] ?? "main";
			this.refresh();
			return { consume: true };
		}
		if (matchesKey(data, "escape")) {
			this.deactivate();
			return { consume: true };
		}
		if (matchesKey(data, Key.enter)) {
			if (this.selectedKey === "main") {
				this.deactivate();
				return { consume: true };
			}
			this.inspectorOpen = true;
			this.refresh();
			const selectedKey = this.selectedKey;
			void Promise.resolve()
				.then(() => this.openInspector(selectedKey))
				.catch((error) => ctx.ui.notify(error instanceof Error ? error.message : String(error), "error"))
				.finally(() => {
					this.inspectorOpen = false;
					this.refresh();
				});
			return { consume: true };
		}

		this.deactivate();
		return undefined;
	}

	render(width: number, theme: Theme): string[] {
		if (this.entries.length === 0) return [];
		if (!this.active) {
			const tokens = this.entries.reduce((total, entry) => total + entry.tokens, 0);
			const label = `${this.entries.length} active ${this.entries.length === 1 ? "agent" : "agents"}`;
			return [truncateToWidth(`  ${theme.fg("muted", label)} · ${theme.fg("dim", `${formatFleetTokens(tokens)} · ↓/← to inspect`)}`, width)];
		}
		const roster = this.rosterKeys();
		const selectedIndex = Math.max(0, roster.indexOf(this.selectedKey));
		const lines = [truncateToWidth(`  ${theme.fg("dim", "↑↓/jk select · enter inspect · esc back")}`, width), ""];
		lines.push(truncateToWidth(`  ${this.bullet(0, selectedIndex, theme)} main`, width));

		const tree = fleetTreeRows(this.entries);
		const selectedTreeIndex = Math.max(0, tree.findIndex((row) => row.kind === "owner" && row.entry.key === this.selectedKey));
		const visibleCount = Math.min(this.maxAgentRows, tree.length);
		const start = selectedTreeIndex < visibleCount ? 0 : selectedTreeIndex - visibleCount + 1;
		const hiddenBelow = tree.length - (start + visibleCount);
		if (start > 0) lines.push(rightAlign("", theme.fg("dim", `↑ ${start} more`), width));
		for (let index = start; index < start + visibleCount; index++) {
			const row = tree[index]!;
			if (row.kind === "owner") {
				const ownerIndex = this.entries.findIndex((entry) => entry.key === row.entry.key);
				lines.push(this.renderEntry(ownerIndex + 1, selectedIndex, row.entry, width, theme));
			} else {
				lines.push(this.renderNestedRow(row.row, row.last, width, theme));
			}
		}
		if (hiddenBelow > 0) lines.push(rightAlign("", theme.fg("dim", `↓ ${hiddenBelow} more`), width));
		return lines;
	}

	private renderEntry(rosterIndex: number, selectedIndex: number, entry: FleetStatusEntry, width: number, theme: Theme): string {
		const description = entry.description?.replace(/\s+/g, " ").trim();
		const agent = entry.modelThinking ? `${entry.agent} (${entry.modelThinking})` : entry.agent;
		const left = `  ${this.bullet(rosterIndex, selectedIndex, theme)} ${theme.fg("muted", agent)} · ${entry.state}${description ? `  ${description}` : ""}`;
		const elapsed = Date.now() - entry.startedAt;
		const right = theme.fg("dim", `${formatFleetElapsed(elapsed)} · ${formatFleetTokens(entry.tokens)}`);
		return rightAlign(left, right, width);
	}

	private renderNestedRow(row: FleetNestedRow, last: boolean, width: number, theme: Theme): string {
		const marker = last ? "└─" : "├─";
		if (row.overflow !== undefined) return truncateToWidth(`    ${marker} ${theme.fg("dim", `+${row.overflow} nested leaves`)}`, width);
		const modelThinking = row.modelThinking ? ` (${row.modelThinking})` : "";
		const activity = row.activity ? ` · ${row.activity}` : "";
		const left = `    ${marker} ${nestedStatusGlyph(row.state, theme)} ${theme.fg("muted", `${row.name}${modelThinking}`)} · ${row.state}${activity}`;
		const elapsed = row.startedAt !== undefined ? ` · ${formatFleetElapsed(Date.now() - row.startedAt)}` : "";
		return truncateToWidth(`${left}${theme.fg("dim", elapsed)}`, width);
	}

	private bullet(rosterIndex: number, selectedIndex: number, theme: Theme): string {
		return rosterIndex === selectedIndex ? theme.fg("accent", ">") : " ";
	}

	private rosterKeys(): string[] {
		return ["main", ...this.entries.map((entry) => entry.key)];
	}

	private clampSelection(): void {
		if (!this.rosterKeys().includes(this.selectedKey)) this.selectedKey = "main";
	}

	private deactivate(): void {
		this.active = false;
		this.selectedKey = "main";
		this.refresh();
	}

	private editorHasFocus(): boolean {
		// pi-tui exposes focus mutation but no focus getter, so inspect the focused
		// component structurally. instanceof is unreliable across jiti module boundaries.
		const focused = (this.tui as unknown as { focusedComponent?: unknown } | undefined)?.focusedComponent;
		if (!focused || typeof focused !== "object") return false;
		const candidate = focused as Partial<EditorComponent>;
		return typeof candidate.render === "function"
			&& typeof candidate.invalidate === "function"
			&& typeof candidate.handleInput === "function"
			&& typeof candidate.getText === "function"
			&& typeof candidate.setText === "function";
	}

	private getRenderKey(): string {
		const now = Date.now();
		return JSON.stringify({
			active: this.active,
			selected: this.selectedKey,
			inspectorOpen: this.inspectorOpen,
			entries: this.entries.map((entry) => this.active
				? [
					entry.key,
					entry.agent,
					entry.state,
					entry.modelThinking,
					entry.description,
					Math.round((now - entry.startedAt) / 1000),
					entry.tokens,
					entry.nestedChildren?.map((child) => [
						child.id,
						child.state,
						child.model,
						child.thinking,
						child.lastUpdate,
						child.steps?.map((step) => [step.agent, step.status, step.model, step.thinking, step.lastActivityAt]),
					]),
				]
				: [entry.key, entry.state, entry.tokens]),
		});
	}

	private getActiveUiContext(): ExtensionContext | undefined {
		const ctx = this.ctx;
		if (!ctx) return undefined;
		try {
			return ctx.hasUI ? ctx : undefined;
		} catch (error) {
			if (!isStaleExtensionContextError(error)) throw error;
			this.clearUiRegistration();
			return undefined;
		}
	}

	private clearUiRegistration(): void {
		if (this.timer) clearInterval(this.timer);
		this.timer = undefined;

		const inputUnsubscribe = this.inputUnsubscribe;
		const ui = this.ui;
		const widgetRegistered = this.widgetRegistered;
		this.inputUnsubscribe = undefined;
		this.ctx = undefined;
		this.ui = undefined;
		this.widgetRegistered = false;
		this.tui = undefined;

		const cleanupErrors: unknown[] = [];
		try {
			inputUnsubscribe?.();
		} catch (error) {
			if (!isStaleExtensionContextError(error)) cleanupErrors.push(error);
		}
		if (ui && widgetRegistered) {
			try {
				ui.setWidget(FLEET_STATUS_WIDGET_KEY, undefined);
			} catch (error) {
				if (!isStaleExtensionContextError(error)) cleanupErrors.push(error);
			}
		}
		if (cleanupErrors.length === 1) throw cleanupErrors[0];
		if (cleanupErrors.length > 1) {
			throw new AggregateError(cleanupErrors, "Failed to clean up FleetView UI registration");
		}
	}
}