/**
 * Host adapter — rich questionnaire form (spec §10.2), rendered via `ctx.ui.custom`.
 *
 * Composes PI's exported TUI widgets — {@link ExtensionSelectorComponent} for single/multi choice and
 * {@link ExtensionInputComponent} for text/chat — inside `ctx.ui.custom<T>` overlays, one per question,
 * collecting into the pure {@link assembleAnswers} core. Single-choice lists options with descriptions,
 * recommended first, plus an implicit "Other → free text" entry; multi-choice is a check/uncheck loop
 * over the same selector; text/chat is a single input.
 *
 * This is the terminal-only path — the capability gate ({@link useRichForm}) selects it only when a
 * real TUI is present, and the extension loads it lazily so RPC/offline never value-imports the widgets
 * (`@earendil-works/pi-tui` is only present inside the live harness). Visual correctness is verified
 * manually, by design.
 */
import {
	type ExtensionCommandContext,
	ExtensionInputComponent,
	ExtensionSelectorComponent,
} from "@earendil-works/pi-coding-agent"
import type { Question, Questionnaire } from "../flow/questionnaire.ts"

/** The slice of the command context the rich form needs: the `ctx.ui.custom` overlay seam. */
type FormContext = Pick<ExtensionCommandContext, "ui">

import {
	collectQuestionnaire,
	DONE_LABEL,
	optionLabel,
	orderedOptions,
	type Picker,
	questionTitle,
	type RawSelection,
} from "./answer-assembly.ts"

/** A {@link Picker} over `ctx.ui.custom` TUI overlays — the primitives single/text collection is shared on. */
function tuiPicker(ctx: FormContext): Picker {
	return {
		pick: (title, labels) => selector(ctx, title, labels),
		text: (title, placeholder) => textInput(ctx, title, placeholder),
	}
}

/**
 * Render the questionnaire as a sequence of rich overlays and return the structured answers keyed by
 * `question.key`. Returns `undefined` if the user cancels any widget (dismiss ≠ cancel — the caller
 * keeps the run blocked).
 */
export function renderRichForm(
	ctx: FormContext,
	questionnaire: Questionnaire,
): Promise<Record<string, unknown> | undefined> {
	return collectQuestionnaire(questionnaire, tuiPicker(ctx), (question) => renderMulti(ctx, question))
}

/** Multi-choice is the one question kind the shared driver cannot serve over `Picker`: a check/uncheck loop over one selector. */
async function renderMulti(ctx: FormContext, question: Question): Promise<RawSelection | undefined> {
	const options = orderedOptions(question)
	const selected = new Set<string>()
	const title = questionTitle(question)
	for (;;) {
		const labels = options.map(
			(candidate) => `${selected.has(candidate.value) ? "[x]" : "[ ]"} ${optionLabel(candidate)}`,
		)
		labels.push(DONE_LABEL)
		const picked = await selector(ctx, title, labels)
		if (picked === undefined) return undefined // cancelled
		if (picked === DONE_LABEL) return { options: [...selected] }
		const option = options[labels.indexOf(picked)]
		if (!option) continue
		if (selected.has(option.value)) selected.delete(option.value)
		else selected.add(option.value)
	}
}

/** One selector overlay: resolves to the chosen label, or `undefined` on cancel. */
function selector(ctx: FormContext, title: string, labels: string[]): Promise<string | undefined> {
	return ctx.ui.custom<string | undefined>(
		(tui, _theme, _keybindings, done) =>
			new ExtensionSelectorComponent(
				title,
				labels,
				(option) => done(option),
				() => done(undefined),
				{ tui },
			),
	)
}

/** One text-input overlay: resolves to the entered string, or `undefined` on cancel. */
function textInput(ctx: FormContext, title: string, placeholder?: string): Promise<string | undefined> {
	return ctx.ui.custom<string | undefined>(
		(tui, _theme, _keybindings, done) =>
			new ExtensionInputComponent(
				title,
				placeholder,
				(value) => done(value),
				() => done(undefined),
				{ tui },
			),
	)
}