import { getLongest } from "../../utils/common.js";
import { CustomHeaders } from "../custom.js";
import type { HeaderEntries, HeaderEntry } from "../index.js";
import type { CommonHeaders } from "./index.js";

export type MonkeyHeader = `// @${string} ${string}` | `// @${string}`;

/**
 * @summary builder for common userscript manager metadata block opening and closing tags
 * @param name optional script name (defaults to UserScript)
 */
export const makeMonkeyTags = (
    name = "UserScript",
): readonly [openTag: string, closeTag: string] => [
    `// ==${name}==`,
    `// ==/${name}==`,
];

/**
 * @summary builder for metadata block header line
 * @param header name-value header entry
 */
export const makeMonkeyHeader = <T extends CommonHeaders>(header: HeaderEntry<T>) => {
    const [name, value] = header;
    return (value ? `// @${name} ${value}` : `// @${name}`) as MonkeyHeader;
};

/**
 * @summary common postprocessor for header generators
 * @param headers list of name-value header entries
 * @param spaces min number of spaces to separate names from values by
 */
export const finalizeMonkeyHeaders = <T extends CommonHeaders<CustomHeaders>>(
    headers: HeaderEntries<T>,
    spaces: number,
) => {
    const [openTag, closeTag] = makeMonkeyTags();

    const longest = getLongest(headers.map(([key]) => key)) + spaces - 1;

    // these should go first
    const important = [
        "name",
        "namespace",
        "version",
        "author",
        "contributor",
        "contributors",
    ];

    const primary = important
        .map(name => headers.find(([header]) => header === name))
        .filter(Boolean) as HeaderEntries<T>;
    const secondary = headers.filter(([header]) => !important.includes(header));

    const sortedHeaders = [
        ...primary,
        ...secondary,
    ];

    const indentedHeaders: HeaderEntries<T> = sortedHeaders.map(([key, val]) => [
        key.padEnd(longest),
        val,
    ]);

    const parsedHeaders: MonkeyHeader[] = indentedHeaders.map(makeMonkeyHeader);

    return [openTag, ...parsedHeaders, closeTag].join("\n");
};