export interface ParsedCliArguments {
  command?: string;
  positional: string[];
  flags: Record<string, string | boolean>;
}

const SHORT_FLAG_MAP: Record<string, string> = {
  c: "config",
  C: "cwd",
  j: "json",
  h: "help",
};

export function parseCliArguments(argv: string[]): ParsedCliArguments {
  const positional: string[] = [];
  const flags: Record<string, string | boolean> = {};
  let parsingFlags = true;

  for (let index = 0; index < argv.length; index += 1) {
    const token = argv[index];

    if (parsingFlags && token === "--") {
      parsingFlags = false;
      continue;
    }

    if (parsingFlags && token.startsWith("--")) {
      const [rawName, inlineValue] = token.slice(2).split("=", 2);
      const name = normalizeFlagName(rawName);
      if (inlineValue !== undefined) {
        flags[name] = coerceValue(inlineValue);
        continue;
      }

      const maybeValue = argv[index + 1];
      if (maybeValue && !maybeValue.startsWith("-")) {
        flags[name] = coerceValue(maybeValue);
        index += 1;
      } else {
        flags[name] = true;
      }
      continue;
    }

    if (parsingFlags && token.startsWith("-") && token.length > 1) {
      const shorts = token.slice(1);
      for (let sIndex = 0; sIndex < shorts.length; sIndex += 1) {
        const flagKey = SHORT_FLAG_MAP[shorts[sIndex]];
        if (!flagKey) continue;
        if (sIndex < shorts.length - 1) {
          flags[flagKey] = true;
          continue;
        }
        const maybeValue = argv[index + 1];
        if (maybeValue && !maybeValue.startsWith("-")) {
          flags[flagKey] = coerceValue(maybeValue);
          index += 1;
        } else {
          flags[flagKey] = true;
        }
      }
      continue;
    }

    positional.push(token);
  }

  const [command, ...rest] = positional;

  return { command, positional: rest, flags };
}

function normalizeFlagName(rawName: string): string {
  return rawName.replace(/-([a-z])/g, (_, letter: string) => letter.toUpperCase());
}

function coerceValue(value: string): string | boolean {
  if (value === "true") return true;
  if (value === "false") return false;
  return value;
}