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

export const STATE_CUSTOM_TYPE = "title-renamer-state";

export interface TitleRenamerState {
	autoRenamed: boolean;
	title?: string;
	triggeredAt: string;
	model: string;
	resolvedModel?: string;
	manual: boolean;
	warnings: string[];
	reset?: boolean;
}

type CustomEntry = {
	type: string;
	customType?: string;
	data?: unknown;
};

function isTitleRenamerState(value: unknown): value is TitleRenamerState {
	if (!value || typeof value !== "object") {
		return false;
	}
	const state = value as Partial<TitleRenamerState>;
	return (
		typeof state.autoRenamed === "boolean" &&
		typeof state.triggeredAt === "string" &&
		typeof state.manual === "boolean"
	);
}

export function getLatestTitleRenamerState(
	entries: readonly CustomEntry[],
): TitleRenamerState | undefined {
	for (let index = entries.length - 1; index >= 0; index--) {
		const entry = entries[index];
		if (
			entry?.type === "custom" &&
			entry.customType === STATE_CUSTOM_TYPE &&
			isTitleRenamerState(entry.data)
		) {
			return entry.data;
		}
	}
	return undefined;
}

export function getLatestResetIndex(entries: readonly CustomEntry[]): number {
	for (let index = entries.length - 1; index >= 0; index--) {
		const entry = entries[index];
		if (
			entry?.type === "custom" &&
			entry.customType === STATE_CUSTOM_TYPE &&
			isTitleRenamerState(entry.data) &&
			entry.data.reset
		) {
			return index;
		}
	}
	return -1;
}

export function hasAutoRenamed(entries: readonly CustomEntry[]): boolean {
	for (let index = entries.length - 1; index >= 0; index--) {
		const entry = entries[index];
		if (
			entry?.type !== "custom" ||
			entry.customType !== STATE_CUSTOM_TYPE ||
			!isTitleRenamerState(entry.data)
		) {
			continue;
		}
		if (entry.data.reset) {
			return false;
		}
		if (entry.data.autoRenamed) {
			return true;
		}
	}
	return false;
}

export function blocksAutoRename(entries: readonly CustomEntry[]): boolean {
	for (let index = entries.length - 1; index >= 0; index--) {
		const entry = entries[index];
		if (
			entry?.type !== "custom" ||
			entry.customType !== STATE_CUSTOM_TYPE ||
			!isTitleRenamerState(entry.data)
		) {
			continue;
		}
		if (entry.data.reset) {
			return false;
		}
		if (entry.data.autoRenamed || (entry.data.manual && !!entry.data.title)) {
			return true;
		}
	}
	return false;
}

export function getLatestTitleToReapply(
	entries: readonly CustomEntry[],
): string | undefined {
	for (let index = entries.length - 1; index >= 0; index--) {
		const entry = entries[index];
		if (
			entry?.type === "custom" &&
			entry.customType === STATE_CUSTOM_TYPE &&
			isTitleRenamerState(entry.data) &&
			entry.data.title
		) {
			return entry.data.title;
		}
	}
	return undefined;
}

export function makeTitleRenamerState(input: {
	autoRenamed: boolean;
	title?: string;
	model: string;
	resolvedModel?: string;
	manual: boolean;
	warnings?: string[];
	reset?: boolean;
	now?: Date;
}): TitleRenamerState {
	return {
		autoRenamed: input.autoRenamed,
		title: input.title,
		triggeredAt: (input.now ?? new Date()).toISOString(),
		model: input.model,
		resolvedModel: input.resolvedModel,
		manual: input.manual,
		warnings: input.warnings ?? [],
		reset: input.reset,
	};
}

export function appendTitleRenamerState(
	pi: Pick<ExtensionAPI, "appendEntry">,
	state: TitleRenamerState,
): void {
	pi.appendEntry(STATE_CUSTOM_TYPE, state);
}