import type { Theme } from "@earendil-works/pi-coding-agent";

import { matchesKey, truncateToWidth } from "@earendil-works/pi-tui";

import type { ChainConfig, ChainStepConfig } from "./agents.js";

import { formatPath, formatScrollInfo, renderFooter, renderHeader, row } from "./render-helpers.js";

export interface ChainDetailState {
	scrollOffset: number;
}

export type ChainDetailAction =
	| { type: "back" }
	| { type: "launch" }
	| {
			type: "edit";
	  };

const CHAIN_DETAIL_VIEWPORT_HEIGHT = 12;

export function buildDependencyMap(steps: ChainStepConfig[]): Map<number, number[]> {
	const outputMap = new Map<string, number>();
	const deps = new Map<number, number[]>();

	for (let i = 0; i < steps.length; i++) {
		const step = steps[i]!;

		if (typeof step.output === "string" && step.output.length > 0) {
			outputMap.set(step.output, i);
		}

		if (Array.isArray(step.reads) && step.reads.length > 0) {
			const sources = step.reads.map((file) => outputMap.get(file)).filter((idx): idx is number => idx !== undefined);
			if (sources.length > 0) {
				deps.set(i, sources);
			}
		}
	}

	return deps;
}

function buildChainDetailLines(chain: ChainConfig, width: number): string[] {
	const contentWidth = width - 3;
	const lines: string[] = [];
	const dependencyMap = buildDependencyMap(chain.steps);
	lines.push(truncateToWidth(chain.description, contentWidth));
	lines.push("");
	lines.push(truncateToWidth(`File: ${formatPath(chain.filePath)}`, contentWidth));
	lines.push("");
	lines.push(truncateToWidth("── Flow ──", contentWidth));

	for (let i = 0; i < chain.steps.length; i++) {
		const step = chain.steps[i]!;
		lines.push(truncateToWidth(`  ${i + 1}  ${step.agent}`, contentWidth));
		const taskPreview = step.task.split("\n")[0] ?? "";
		lines.push(truncateToWidth(`     task: ${taskPreview || "(none)"}`, contentWidth));
		if (Array.isArray(step.reads) && step.reads.length > 0) {
			const sources = dependencyMap.get(i);
			const fromText = sources && sources.length > 0 ? ` (from ${sources.map((s) => s + 1).join(", ")})` : "";
			lines.push(truncateToWidth(`     ← reads: ${step.reads.join(", ")}${fromText}`, contentWidth));
		} else if (step.reads === false) {
			lines.push(truncateToWidth("     ← reads: (disabled)", contentWidth));
		}
		if (typeof step.output === "string" && step.output.length > 0) {
			lines.push(truncateToWidth(`     → output: ${step.output}`, contentWidth));
		} else if (step.output === false) {
			lines.push(truncateToWidth("     → output: (disabled)", contentWidth));
		}
		if (step.model) {
			lines.push(truncateToWidth(`     model: ${step.model}`, contentWidth));
		}
		if (step.skills !== undefined) {
			const skillsText =
				step.skills === false ? "(disabled)" : step.skills.length > 0 ? step.skills.join(", ") : "(none)";
			lines.push(truncateToWidth(`     skills: ${skillsText}`, contentWidth));
		}
		if (step.progress !== undefined) {
			lines.push(truncateToWidth(`     progress: ${step.progress ? "on" : "off"}`, contentWidth));
		}
		lines.push("");
	}

	if (chain.steps.length === 0) {
		lines.push(truncateToWidth("(no steps)", contentWidth));
	}

	return lines;
}

export function handleChainDetailInput(state: ChainDetailState, data: string): ChainDetailAction | undefined {
	if (matchesKey(data, "escape") || matchesKey(data, "ctrl+c")) {
		return { type: "back" };
	}

	if (data === "l") {
		return { type: "launch" };
	}

	if (data === "e") {
		return { type: "edit" };
	}

	if (matchesKey(data, "up")) {
		state.scrollOffset--;
		return;
	}

	if (matchesKey(data, "down")) {
		state.scrollOffset++;
		return;
	}

	if (matchesKey(data, "pageup") || matchesKey(data, "shift+up")) {
		state.scrollOffset -= CHAIN_DETAIL_VIEWPORT_HEIGHT;
		return;
	}

	if (matchesKey(data, "pagedown") || matchesKey(data, "shift+down")) {
		state.scrollOffset += CHAIN_DETAIL_VIEWPORT_HEIGHT;
		return;
	}

	return;
}

export function renderChainDetail(state: ChainDetailState, chain: ChainConfig, width: number, theme: Theme): string[] {
	const lines: string[] = [];
	const scopeBadge = chain.source === "user" ? "[user]" : "[proj]";
	lines.push(renderHeader(` ${chain.name} [chain] ${scopeBadge} `, width, theme));
	lines.push(row("", width, theme));

	const contentLines = buildChainDetailLines(chain, width);
	const maxOffset = Math.max(0, contentLines.length - CHAIN_DETAIL_VIEWPORT_HEIGHT);
	state.scrollOffset = Math.max(0, Math.min(state.scrollOffset, maxOffset));
	const visible = contentLines.slice(state.scrollOffset, state.scrollOffset + CHAIN_DETAIL_VIEWPORT_HEIGHT);
	for (const line of visible) {
		lines.push(row(` ${line}`, width, theme));
	}
	for (let i = visible.length; i < CHAIN_DETAIL_VIEWPORT_HEIGHT; i++) {
		lines.push(row("", width, theme));
	}

	const scrollInfo = formatScrollInfo(
		state.scrollOffset,
		Math.max(0, contentLines.length - (state.scrollOffset + CHAIN_DETAIL_VIEWPORT_HEIGHT)),
	);
	lines.push(row(scrollInfo ? ` ${theme.fg("dim", scrollInfo)}` : "", width, theme));
	lines.push(renderFooter(" [l]aunch  [e]dit  [↑↓] scroll  [esc] back ", width, theme));
	return lines;
}