// the /lore command surface: what the picker offers while typing, and the help card.
// one place, so the picker, the help, and the handler cannot drift apart.
import type { Theme } from "@earendil-works/pi-coding-agent";
import { Text } from "@earendil-works/pi-tui";
import type { AutocompleteItem } from "@earendil-works/pi-tui";

export type Subcommand = { name: string; args?: string; what: string; group: "read" | "write" | "share" | "account" };

export const SUBCOMMANDS: readonly Subcommand[] = [
	{ name: "", what: "this project's space: a few lines and a link", group: "read" },
	{ name: "all", what: "every line", group: "read" },
	{ name: "mine", what: "only lines you wrote", group: "read" },
	{ name: "note", args: "<text>", what: "save text exactly as typed", group: "write" },
	{ name: "use", args: "<key>", what: "use a space you name for this project", group: "write" },
	{ name: "share", args: "<handle>", what: "let someone read and add to this space", group: "share" },
	{ name: "unshare", args: "<handle>", what: "take that back", group: "share" },
	{ name: "members", what: "who has been added", group: "share" },
	{ name: "join", args: "<owner> <key>", what: "use a space someone shared with you", group: "share" },
	{ name: "leave", what: "stop using the joined space here", group: "share" },
	{ name: "as", args: "[handle]", what: "switch account; no handle opens a picker", group: "account" },
	{ name: "login", args: "[handle]", what: "sign in through your PDS in the browser", group: "account" },
	{ name: "logout", args: "[handle]", what: "drop an account", group: "account" },
	{ name: "help", what: "this list", group: "read" },
] as const;

export const DESCRIPTION = "breadcrumbs on your PDS. /lore help lists the subcommands";

const GROUPS = ["read", "write", "share", "account"] as const;

export type Sources = {
	accounts: readonly string[];
	actors: (q: string) => Promise<AutocompleteItem[]>;
	/** keys of the spaces the current account owns, for `use` */
	keys: () => Promise<readonly string[]>;
};

/** items for the picker: subcommands until the first space, then whatever the subcommand takes. */
export function completions(prefix: string, { accounts, actors, keys }: Sources): AutocompleteItem[] | Promise<AutocompleteItem[]> | null {
	const m = prefix.match(/^(\S*)(?:\s+(.*))?$/);
	const head = m?.[1] ?? "";
	const rest = m?.[2];
	if (rest === undefined) {
		return SUBCOMMANDS.filter((c) => c.name && c.name.startsWith(head)).map((c) => ({
			value: c.name,
			label: c.args ? `${c.name} ${c.args}` : c.name,
			description: c.what,
		}));
	}
	if (head === "as" || head === "logout") {
		return accounts.filter((h) => h.startsWith(rest)).map((h) => ({ value: `${head} ${h}`, label: h, description: "account" }));
	}
	if ((head === "share" || head === "unshare" || head === "join" || head === "login") && !rest.includes(" ") && rest.length >= 2) {
		return actors(rest).then((items) => items.map((i) => ({ ...i, value: `${head} ${i.value}` })));
	}
	if (head === "use" && !rest.includes(" ")) {
		return keys().then((all) => all.filter((k) => k.startsWith(rest)).map((k) => ({ value: `use ${k}`, label: k, description: "a space you own" })));
	}
	return null;
}

type HelpTheme = Pick<Theme, "fg" | "bold">;

export function renderHelp(account: string | null, accounts: readonly string[], theme: HelpTheme): Text {
	const lines: string[] = [];
	const who = account ? `${theme.fg("accent", account)}${accounts.length > 1 ? theme.fg("dim", ` · also ${accounts.filter((a) => a !== account).join(", ")} · /lore as switches`) : ""}` : theme.fg("warning", "not signed in · /lore login <handle>");
	lines.push(`${theme.fg("accent", theme.bold("/lore"))}  ${who}`);
	for (const group of GROUPS) {
		lines.push("", theme.fg("muted", theme.bold(group)));
		for (const c of SUBCOMMANDS.filter((s) => s.group === group)) {
			const cmd = `/lore${c.name ? ` ${c.name}` : ""}${c.args ? ` ${c.args}` : ""}`;
			lines.push(`  ${theme.fg("accent", cmd.padEnd(28))}${theme.fg("text", c.what)}`);
		}
	}
	lines.push("", theme.fg("dim", "  a space someone shared with you: /lore join <their handle> <the key they gave you>"));
	return new Text(lines.join("\n"), 0, 0);
}