// The version a project declares, by Koh's own rule (`src/build/version.v` in Koh 3): the first
// source that answers wins, so a `VERSION` file overrides everything, and nothing is evaluated: a
// value built from a variable or a call is skipped and the next source tried. A source that answers
// with something that is not a version means no version, as Koh then refuses to publish.

const GRADLE_FILES = [
	"app/build.gradle.kts",
	"app/build.gradle",
	"build.gradle.kts",
	"build.gradle",
];
const VERSION = /^[A-Za-z0-9.-]{1,32}$/;
const ASCII_SPACE = /^[ \n\t\v\f\r]+|[ \n\t\v\f\r]+$/g;

/** The declared version, reading files at one save through `read` (null for a missing file). */
export function declaredVersion(read: (path: string) => string | null): string | null {
	const sources: (() => string | null)[] = [
		() => read("VERSION")?.replace(ASCII_SPACE, "") || null,
		() => lineVersion(read("build.zig.zon"), ".version"),
		() => lineVersion(read("v.mod"), "version"),
		() => lineVersion(read("package.json"), '"version"'),
		() => lineVersion(read("Cargo.toml"), "version"),
		() => plistVersion(read("Info.plist")),
		...GRADLE_FILES.map((path) => () => gradleVersion(read(path))),
	];
	for (const source of sources) {
		const value = source();
		if (value !== null) return VERSION.test(value) ? value : null;
	}
	return null;
}

// The value of the first line the key starts that assigns a quoted literal.
function lineVersion(text: string | null, key: string): string | null {
	for (const line of text?.split(/\r\n|[\r\n]/) ?? []) {
		const trimmed = line.replace(/^[ \t]+/, "");
		if (trimmed === "" || trimmed.startsWith("//") || trimmed.startsWith("#")) continue;
		if (!trimmed.startsWith(key)) continue;
		const value = literalAfter(trimmed, key.length);
		if (value !== null) return value;
	}
	return null;
}

// The quoted literal right after the key, an optional `=` or `:` and any spaces.
function literalAfter(line: string, from: number): string | null {
	let at = from;
	while (at < line.length && " \t=:".includes(line[at] as string)) at++;
	const quote = line[at];
	if (quote !== '"' && quote !== "'") return null;
	const end = line.indexOf(quote, at + 1);
	return end < 0 ? null : line.slice(at + 1, end);
}

// CFBundleShortVersionString: its value is in the <string> after the key, not on the key's line.
function plistVersion(text: string | null): string | null {
	const at = text?.indexOf("<key>CFBundleShortVersionString</key>") ?? -1;
	if (!text || at < 0) return null;
	const rest = text.slice(at);
	const open = rest.indexOf("<string>");
	const close = rest.indexOf("</string>");
	if (open < 0 || close <= open + "<string>".length) return null;
	return rest.slice(open + "<string>".length, close).replace(ASCII_SPACE, "") || null;
}

// `versionName` assigned a quoted literal, Kotlin (`= "1.2"`) or Groovy (`"1.2"`); comments and
// `versionNameSuffix` are not it.
function gradleVersion(text: string | null): string | null {
	for (const line of text?.split(/\r\n|[\r\n]/) ?? []) {
		const trimmed = line.replace(/^[ \t]+/, "");
		if (trimmed === "" || /^(\/\/|\/\*|\*)/.test(trimmed)) continue;
		if (!/^versionName[ =]/.test(trimmed)) continue;
		const value = literalAfter(trimmed, "versionName".length);
		if (value !== null) return value;
	}
	return null;
}