// The variable key registry (REQ-VAR-1, note section 2, addendum A section
// 7). Every key is declared here once, with its type, the layers allowed to
// set it and its merge rule. A key that isn't here refuses, and so does a
// key set at a layer it isn't allowed in.
//
// Layers, least to most specific:
//   system    ~/.config/mosaic-dev/config.json, resolved by mosaic-config.mjs
//   business  vars in businesses/<id>.json
//   project   vars in <root>/.mosaic/project.json, then that file's
//             roles.<instance>.vars (still the project layer, applied after)
//   agent     roles.<instance>.vars in the business file
//
// Merge rules:
//   replace    the most specific layer that sets the key wins
//   intersect  every layer that sets the key narrows it; nothing widens

import { refuse } from "./errors.mjs";
import { ACTIONS, NETWORKS, TOOLS } from "./vocabulary.mjs";
import { isPlainObject, requireDistinctList, requirePositiveInt, requireString } from "./util.mjs";

export const LAYERS = Object.freeze(["system", "business", "project", "agent"]);

const BRANCH = /^(?!-)(?!.*\.\.)(?!.*\/\/)(?!.*\.lock$)[A-Za-z0-9._/-]{1,100}(?<![./])$/;

function string(max = 200) {
  return (v, key) => requireString(v, `variable ${key}`, { max });
}

function oneOf(values) {
  return (v, key) => {
    if (!values.includes(v)) refuse(`variable ${key} must be one of: ${values.join(", ")} (got ${JSON.stringify(v)})`);
    return v;
  };
}

function integer(min) {
  return (v, key) => {
    if (!Number.isSafeInteger(v) || v < min) refuse(`variable ${key} must be an integer of at least ${min} (got ${JSON.stringify(v)})`);
    return v;
  };
}

// http or https, no user info, query or fragment, no trailing slash.
function baseUrl(v, key) {
  requireString(v, `variable ${key}`, { max: 300 });
  let url;
  try {
    url = new URL(v);
  } catch {
    refuse(`variable ${key} must be an http or https URL (got ${JSON.stringify(v)})`);
  }
  if (!["http:", "https:"].includes(url.protocol) || url.username || url.password || url.search || url.hash || v.endsWith("/")) {
    refuse(`variable ${key} must be an http or https base URL with no credentials, query, fragment or trailing slash`);
  }
  return v;
}

function branch(v, key) {
  if (typeof v !== "string" || !BRANCH.test(v)) refuse(`variable ${key} must be a git branch name (got ${JSON.stringify(v)})`);
  return v;
}

function list(check, { nonEmpty = true } = {}) {
  return (v, key) => requireDistinctList(v, `variable ${key}`, (item) => check(item, `${key} entry`), { nonEmpty });
}

function boolean(v, key) {
  if (typeof v !== "boolean") refuse(`variable ${key} must be true or false (got ${JSON.stringify(v)})`);
  return v;
}

function absolutePath(v, key) {
  if (typeof v !== "string" || !v.startsWith("/") || v.includes("\0")) refuse(`variable ${key} must be an absolute path`);
  return v;
}

const def = (layers, check, extra = {}) => Object.freeze({ layers: Object.freeze(layers), merge: "replace", check, default: undefined, ...extra });

export const REGISTRY = Object.freeze({
  // System. mosaic-config.mjs owns their validation; these checks only
  // keep the resolver honest about types.
  environment: def(["system"], string(64)),
  dataRoot: def(["system"], absolutePath),
  "execution.backend": def(["system"], string(64)),
  "execution.provider": def(["system"], string(64)),
  "execution.model": def(["system"], string(200)),
  "execution.adapter": def(["system"], string(64)),

  // Business.
  "tracker.kind": def(["business"], oneOf(["vikunja"]), { default: "vikunja" }),
  "tracker.baseUrl": def(["business"], baseUrl),
  "tracker.reconcileMinutes": def(["business"], integer(1), { default: 60 }),
  "tracker.pollSeconds": def(["business", "project"], integer(10), { default: 30 }),
  "human.discordUserId": def(["business"], (v, key) => {
    if (typeof v !== "string" || !/^[1-9][0-9]{16,19}$/.test(v)) refuse(`variable ${key} must be a Discord user id, 17 to 20 digits as a string`);
    return v;
  }),
  "gitea.baseUrl": def(["business"], baseUrl),
  // On: the bus binds a tester from tester-cli.mjs for PM tests (row 110). Read at bus start.
  "bus.tester": def(["business"], boolean, { default: false }),

  // Project.
  "tracker.project": def(["project"], (v, key) => requirePositiveInt(v, `variable ${key}`)),
  // On: the tracker project is the root of a tree, and sync reads its descendants too.
  "tracker.descendants": def(["project"], boolean, { default: false }),
  "git.workingBranch": def(["project"], branch),
  "git.protectedBranches": def(["project"], list(branch)),
  suites: def(["project"], list(string(300))),
  "issues.repo": def(["project"], (v, key) => {
    if (typeof v !== "string" || !/^[A-Za-z0-9_.-]{1,100}\/[A-Za-z0-9_.-]{1,100}$/.test(v)) refuse(`variable ${key} must be owner/name`);
    return v;
  }),

  // Agent: one role instance.
  harness: def(["agent"], oneOf(["pi", "claude-code"])),
  model: def(["agent"], string(200)),
  thinking: def(["agent"], oneOf(["off", "minimal", "low", "medium", "high", "xhigh"])),

  // Limits narrow the role definition's ceilings. limits.authority is an
  // allowlist: a role action it doesn't name becomes gated.
  "limits.tools": def(["business", "project", "agent"], list((v, key) => {
    if (!TOOLS.includes(v)) refuse(`variable ${key} names an unsupported tool: ${JSON.stringify(v)}`);
  }, { nonEmpty: false }), { merge: "intersect" }),
  "limits.network": def(["business", "project", "agent"], oneOf(NETWORKS), { merge: "intersect" }),
  "limits.authority": def(["business", "project", "agent"], list((v, key) => {
    if (!ACTIONS.includes(v)) refuse(`variable ${key} names an unknown action: ${JSON.stringify(v)}`);
  }, { nonEmpty: false }), { merge: "intersect" }),
});

// Check one layer's vars object. `where` names the file and path for the
// message. Returns a frozen copy with checked values.
export function checkVars(vars, layer, where) {
  if (!LAYERS.includes(layer)) throw new Error(`unknown layer ${layer}`);
  if (!isPlainObject(vars)) refuse(`${where} must be a JSON object`);
  const out = {};
  for (const [key, value] of Object.entries(vars)) {
    const entry = Object.hasOwn(REGISTRY, key) ? REGISTRY[key] : null;
    if (!entry) refuse(`${where}: unknown variable ${JSON.stringify(key)}`);
    if (!entry.layers.includes(layer)) refuse(`${where}: variable ${key} can't be set at the ${layer} layer (allowed: ${entry.layers.join(", ")})`);
    out[key] = entry.check(value, key);
  }
  return Object.freeze(out);
}

function narrower(a, b) {
  return NETWORKS.indexOf(a) <= NETWORKS.indexOf(b) ? a : b;
}

// Merge checked layers, given least specific first as [{ layer, source,
// vars }]. Returns { vars, provenance }. provenance[key] is the source
// that set a replace key, or the list of sources that narrowed a limit.
export function mergeVars(layers) {
  const vars = {};
  const provenance = {};
  for (const [key, entry] of Object.entries(REGISTRY)) {
    if (entry.default !== undefined) {
      vars[key] = entry.default;
      provenance[key] = "default";
    }
  }
  for (const { source, vars: layerVars } of layers) {
    for (const [key, value] of Object.entries(layerVars)) {
      const entry = REGISTRY[key];
      if (entry.merge === "replace" || vars[key] === undefined) {
        vars[key] = value;
        provenance[key] = entry.merge === "replace" ? source : [source];
      } else if (key === "limits.network") {
        vars[key] = narrower(vars[key], value);
        provenance[key].push(source);
      } else {
        vars[key] = vars[key].filter((item) => value.includes(item));
        provenance[key].push(source);
      }
    }
  }
  return { vars, provenance };
}