import { fnv1a64 } from "../worker/replay.mjs";
import { normalizeWorkspacePath } from "./runtime.mjs";

export const INI_SCHEMA = "ini-resource-graph.v1";
export const INI_ERRORS = Object.freeze({
  missing: "ini_source_missing",
  cycle: "ini_include_cycle",
  depth: "ini_include_depth",
  section: "ini_section_invalid",
  key: "ini_key_invalid",
  assignment: "ini_assignment_invalid",
  variable: "ini_variable_missing",
  path: "ini_path_invalid",
});

function clone(value) { return structuredClone(value); }
function error(code, path, line, message = code, extra = {}) {
  return Object.assign(new Error(message), { code, source: path, line, column: 1, ...extra });
}
function stripComment(line) {
  let quote = null;
  for (let index = 0; index < line.length; index += 1) {
    const char = line[index];
    if ((char === "\"" || char === "'") && (!quote || quote === char)) quote = quote ? null : char;
    if (!quote && (char === ";" || char === "#")) return line.slice(0, index);
  }
  return line;
}
function resolveWorkspaceRelative(basePath, value) {
  const parts = basePath.split("/");
  parts.pop();
  for (const part of value.replaceAll("\\", "/").split("/")) {
    if (!part || part === ".") continue;
    if (part === "..") {
      if (!parts.length) throw error(INI_ERRORS.path, basePath, 0, "ini_include_path_escape");
      parts.pop();
      continue;
    }
    parts.push(part);
  }
  return normalizeWorkspacePath(`/workspace/${parts.join("/")}`);
}
function resolveInclude(basePath, includePath) {
  if (includePath.startsWith("/") || includePath.includes("\\")) throw error(INI_ERRORS.path, basePath, 0, "ini_include_path_invalid");
  if (includePath.startsWith("linuxcnc/")) return normalizeWorkspacePath(`/workspace/${includePath}`);
  return resolveWorkspaceRelative(basePath, includePath);
}
function expand(value, variables, path, line) {
  return value.replace(/\$\{([^}]+)\}|\$\(([^)]+)\)|\$([A-Za-z_][A-Za-z0-9_]*)/g, (match, brace, paren, plain) => {
    const name = brace ?? paren ?? plain;
    if (!(name in variables)) throw error(INI_ERRORS.variable, path, line, "ini_variable_missing", { variable: name });
    return String(variables[name]);
  });
}

export function parseIni({ workspace, entrypoint, variables = {}, maxDepth = 32 } = {}) {
  if (!workspace || typeof workspace.read !== "function") throw new Error("ini_workspace_required");
  const root = normalizeWorkspacePath(entrypoint);
  const sections = {};
  const entries = [];
  const includes = [];
  const diagnostics = [];
  const graph = [];
  const active = [];
  const vars = { ...variables };

  function parseFile(path, depth) {
    if (depth > maxDepth) throw error(INI_ERRORS.depth, path, 0, "ini_include_depth", { maxDepth });
    if (active.includes(path)) throw error(INI_ERRORS.cycle, path, 0, "ini_include_cycle", { cycle: [...active, path] });
    active.push(path);
    let source;
    try { source = workspace.read(`/workspace/${path}`); } catch (cause) {
      active.pop();
      throw error(INI_ERRORS.missing, path, 0, "ini_source_missing", { cause: String(cause?.message ?? cause) });
    }
    graph.push(path);
    let section = "";
    const lines = source.split(/\r?\n/);
    lines.forEach((rawLine, offset) => {
      const lineNumber = offset + 1;
      const hashInclude = rawLine.trim().match(/^#INCLUDE\s+(.+)$/i);
      if (hashInclude) {
        const rawInclude = hashInclude[1].trim().replace(/^['"]|['"]$/g, "");
        let child;
        try { child = resolveInclude(path, expand(rawInclude, vars, path, lineNumber)); } catch (cause) { throw cause.code ? cause : error(INI_ERRORS.path, path, lineNumber, "ini_include_path_invalid"); }
        includes.push({ source: path, line: lineNumber, path: child });
        parseFile(child, depth + 1);
        return;
      }
      const clean = stripComment(rawLine).trim();
      if (!clean) return;
      const includeMatch = clean.match(/^(?:include|INCLUDE)\s*(?:=\s*)?(.+)$/);
      if (includeMatch) {
        const rawInclude = includeMatch[1].trim().replace(/^['"]|['"]$/g, "");
        let child;
        try { child = resolveInclude(path, expand(rawInclude, vars, path, lineNumber)); } catch (cause) { throw cause.code ? cause : error(INI_ERRORS.path, path, lineNumber, "ini_include_path_invalid"); }
        includes.push({ source: path, line: lineNumber, path: child });
        parseFile(child, depth + 1);
        return;
      }
      const sectionMatch = clean.match(/^\[([^\]]+)\]$/);
      if (sectionMatch) {
        section = sectionMatch[1].trim();
        if (!section || /[\0\r\n]/.test(section)) throw error(INI_ERRORS.section, path, lineNumber, "ini_section_invalid");
        if (!sections[section]) sections[section] = {};
        return;
      }
      const assignment = clean.match(/^([^=:#]+?)\s*(?:=|:)\s*(.*)$/);
      if (!assignment || !section) throw error(!section ? INI_ERRORS.section : INI_ERRORS.assignment, path, lineNumber, !section ? "ini_section_invalid" : "ini_assignment_invalid");
      const key = assignment[1].trim();
      if (!/^[A-Za-z_][A-Za-z0-9_.-]*$/.test(key)) throw error(INI_ERRORS.key, path, lineNumber, "ini_key_invalid");
      const value = expand(assignment[2].trim(), vars, path, lineNumber);
      sections[section][key] = value;
      if (section.toUpperCase() === "VAR" || section.toUpperCase() === "VARIABLES") vars[key] = value;
      entries.push({ source: path, line: lineNumber, section, key, value });
    });
    active.pop();
  }

  parseFile(root, 0);
  const normalizedSections = Object.fromEntries(Object.keys(sections).sort().map((name) => [name, Object.fromEntries(Object.keys(sections[name]).sort().map((key) => [key, sections[name][key]]))]));
  const result = {
    schema: INI_SCHEMA,
    entrypoint: root,
    sections: normalizedSections,
    entries,
    includes,
    graph: [...new Set(graph)],
    variables: Object.fromEntries(Object.keys(vars).sort().map((key) => [key, vars[key]])),
    diagnostics,
  };
  return { ...result, state_hash: fnv1a64(result) };
}