/**
 * BuildModel — the data layer for the build console (the deck's BUILD
 * button on a planet surface). Pure functions over data/builds.json —
 * no scene, no Phaser (dev/builds.test.mjs runs it in Node; the browser
 * side is js/ui/BuildWindow.js).
 *
 * Research UNLOCKS a build (data/research/*.json → unlocks.builds);
 * building then costs resources + time on a planet and applies the effect
 * (e.g. the level-2 tether). The availability rules here mirror the
 * research model (js/research/ResearchModel.js):
 *
 *   - `requires`        — "category/node" ids that must be researched
 *   - `planetRequires`  — world-state gates (e.g. tetherLevel ≥ 1)
 *   - `isBuilt`         — one-off builds are not built twice on a planet
 *   - `cost`            — paid in full when the build starts (minerals/credits)
 *
 *   categories()             → data/builds.json → categories
 *   loadBuilds(catId)        → { id, label, accent, builds, order }
 *   defById(id)              → the definition for one build id (any category)
 *   startingPairs()          → [ [planet, buildId], … ] pre-installed on a fresh run
 *   missingRequirements(def) → unmet gates (research + planet) as strings
 *   isAvailable(def, ctx)    → gates met AND not already built on the planet
 *   rowState(def, ctx, active, id) → 'built' | 'active' | 'available' | 'locked'
 *   costLines(def)           → [{ res, amount }] for the cost readout
 *   canAfford(def, minerals) → every line is covered
 *
 * `ctx` is the caller's view of the world (the window composes it from
 * scene seams; the tests compose it by hand):
 *   { isResearchUnlocked(catId, nodeId), tetherLevel(planetName),
 *     isBuilt(planetName, buildId) }
 */
import { config } from '../config/Config.js';
import { buildDefs } from '../research/ResearchModel.js';

/** The category registry (data/builds.json → categories). */
export function categories() {
  const cats = config.get('builds.categories', []);
  return Array.isArray(cats) ? cats : [];
}

/**
 * Load one build category (the id → its builds + registry entry).
 * Unknown ids resolve to the default category; a missing registry entry
 * is a warning (dev tools) with a neutral accent.
 */
export function loadBuilds(catId) {
  const cats = categories();
  const meta = cats.find((c) => c.id === catId)
    ?? cats.find((c) => c.id === config.get('builds.defaultCategory', cats[0]?.id))
    ?? null;
  if (!meta) {
    console.warn('[builds] no categories in data/builds.json');
    return { id: String(catId), label: String(catId), accent: '#8fa3c8', builds: {}, order: [] };
  }
  const defs = buildDefs();
  const builds = {};
  for (const [id, def] of Object.entries(defs)) {
    if (def?.category === meta.id) builds[id] = def;
  }
  const order = Object.keys(builds);
  if (!order.length) console.warn(`[builds] category "${meta.id}" has no builds (data/builds.json)`);
  return { ...meta, builds, order };
}

/** Look up one build definition by id (any category); null if unknown. */
export function defById(id) {
  const defs = buildDefs();
  return Object.prototype.hasOwnProperty.call(defs, id) ? defs[id] : null;
}

/**
 * SHIP-SCOPED build (data/builds.json → targets: ["ship"]): the effect
 * is on the ship (the mining arms + storage), not the planet — installed
 * from any planet's console, counted as BUILT wherever the ship lands
 * (BuildState.isBuiltAnywhere), never re-bought. Planet-scoped builds
 * (targets: ["planet"]) are the ordinary one-off surface installs.
 */
export function isShipScoped(def) {
  return Array.isArray(def?.targets) && def.targets.includes('ship');
}

/**
 * [planet, buildId] pairs pre-installed on a fresh run — the home world
 * starts with its level-1 tether (data/builds.json → tether-l1.starting).
 * 'home' is the seed-independent home key (the scene resolves it to the
 * home world's name before seeding BuildState).
 */
export function startingPairs() {
  const out = [];
  for (const [id, def] of Object.entries(buildDefs())) {
    for (const p of def?.starting ?? []) out.push([p, id]);
  }
  return out;
}

/** Unmet gates for a build, as short strings (research first, then the planet). */
export function missingRequirements(def, ctx) {
  const out = [];
  for (const req of def?.requires ?? []) {
    const i = req.indexOf('/');
    if (i < 0) continue;
    const cat = req.slice(0, i);
    const node = req.slice(i + 1);
    if (!ctx.isResearchUnlocked(cat, node)) out.push(`RESEARCH: ${node.toUpperCase()}`);
  }
  const needTether = def?.planetRequires?.tetherLevel;
  if (typeof needTether === 'number' && (ctx.tetherLevel() ?? 0) < needTether) {
    out.push(`TETHER ≥ L${needTether}`);
  }
  return out;
}

/** Gates met (research + planet) AND not already built on this planet. */
export function isAvailable(def, ctx) {
  if (!def) return false;
  if (ctx.isBuilt()) return false;
  return missingRequirements(def, ctx).length === 0;
}

/** The row's state for the list (the list paints from this). */
export function rowState(def, ctx, active, id) {
  if (ctx.isBuilt()) return 'built';
  if (active && active.build === id) return 'active';
  return isAvailable(def, ctx) ? 'available' : 'locked';
}

/** Cost lines for the readout (data → minerals/credits amounts). */
export function costLines(def) {
  const cost = def?.cost;
  if (!cost || typeof cost !== 'object') return [];
  return Object.entries(cost)
    .filter(([, amount]) => typeof amount === 'number' && amount > 0)
    .map(([res, amount]) => ({ res, amount }));
}

/**
 * Can the player pay the full cost. `wallet` is a number (shorthand for
 * { minerals: n } — today's economy) or a { res: amount } map.
 */
export function canAfford(def, wallet) {
  const w = typeof wallet === 'number' ? { minerals: wallet } : wallet;
  return costLines(def).every((l) => (w?.[l.res] ?? 0) >= l.amount);
}