/**
 * lib/providers/index.mjs — Static provider registry
 *
 * Authority: ADR 0002 § "Loading model"
 *
 * This file is a hand-maintained static enumeration. There is no filesystem
 * scan, no dynamic discovery, no npm-installed plugin loading. Adding a
 * provider requires: (1) write lib/providers/<name>.mjs, (2) add one import +
 * one entry to STATIC_REGISTRY below, (3) README § "Supported Providers",
 * (4) inclusion ADR per ADR 0006.
 *
 * At D4 (Phase 1 Day 2), the anthropic plugin is added to STATIC_REGISTRY
 * as a Candidate. It is NOT Enabled by default — a config with
 * { enabled: { anthropic: true } } is required, which only happens after D5
 * E2E audit passes per ALIGNMENT.md § Provider Inventory.
 *
 * At D6 (Phase 1 Day 4), the openai (Codex) plugin is added to STATIC_REGISTRY
 * as a Candidate. Enabled by { enabled: { openai: true } } after D7 E2E audit.
 *
 * At D8 (Phase 1 Day 5), the mistral (Mistral Vibe) plugin is added to
 * STATIC_REGISTRY as a Candidate. Enabled by { enabled: { mistral: true } }
 * after D-later E2E audit. Authority: ADR 0006 Tier D classification for
 * Mistral Vibe (Le Chat Pro); docs-based authority from
 * https://docs.mistral.ai/mistral-vibe/terminal/quickstart.
 *
 * D17 (Finding 12+13): alias resolution is centralised in getProviderForModel().
 * models-registry.json is the single source of truth for alias→canonical mapping.
 * All provider plugins expose canonical IDs only in their models[] field.
 */

import { validateProvider } from './base.mjs';
import anthropicDefault from './anthropic.mjs';
import codexDefault from './codex.mjs';
import mistralDefault from './mistral.mjs';
import modelsRegistryRaw from '../../models-registry.json' with { type: 'json' };

// Normalize default export pattern
const anthropic = anthropicDefault;
const codex = codexDefault;
const mistral = mistralDefault;

// ── Static registry ───────────────────────────────────────────────────────

const STATIC_REGISTRY = [
  anthropic,
  codex,
  mistral,
];

// ── Alias map (built once at module load) ─────────────────────────────────
// Maps aliasString → { providerName: string, canonicalModel: string }
// Sourced from models-registry.json providers[*].aliases — the SPOT for alias
// definitions per D17 Finding 12 fix. Each provider plugin's models[] contains
// only canonical IDs; this map is consulted by getProviderForModel() to resolve
// alias strings before the direct-lookup fallback.
//
// Example entries:
//   'sonnet'        → { providerName: 'anthropic', canonicalModel: 'claude-sonnet-4-6' }
//   'devstral'      → { providerName: 'mistral',   canonicalModel: 'devstral-2-25-12' }
//   'codex'         → { providerName: 'openai',    canonicalModel: 'gpt-5.3-codex' }
const _aliasMap = new Map();
for (const [providerName, providerEntry] of Object.entries(
  modelsRegistryRaw?.providers ?? {},
)) {
  for (const [alias, canonicalModel] of Object.entries(
    providerEntry?.aliases ?? {},
  )) {
    _aliasMap.set(alias, { providerName, canonicalModel });
  }
}

// ── Registry functions ────────────────────────────────────────────────────

/**
 * Loads and validates providers, filtering by the enabled set in config.
 * At D4, the anthropic provider is Candidate only — it will not appear in
 * the loaded Map unless config.enabled.anthropic === true (set by D5 after E2E).
 *
 * @param {{ enabled?: Record<string,boolean> }} [config={}]
 * @returns {Map<string, import('./base.mjs').ProviderContractV1>}
 */
export function loadProviders(config = {}) {
  const loaded = new Map();

  for (const p of STATIC_REGISTRY) {
    const { valid, errors } = validateProvider(p);
    if (!valid) {
      throw new Error(`Provider ${p?.name ?? 'unknown'} fails contract validation: ${errors.join('; ')}`);
    }

    const enabled = config.enabled?.[p.name] === true;
    if (enabled) {
      loaded.set(p.name, p);
    }
  }

  return loaded;
}

/**
 * Returns the provider in `loadedProviders` that serves `modelString`, with
 * alias resolution. D17 Finding 12+13: this is the single lookup point (SPOT)
 * for model→provider routing. All callers (including buildDefaultChain) must
 * use this function instead of duplicating the scan loop.
 *
 * Resolution order:
 *   1. Alias lookup: if modelString is a known alias in models-registry.json
 *      AND the resolved provider is in loadedProviders (enabled), return the
 *      match with canonicalModel set to the canonical ID.
 *   2. Direct lookup: scan loadedProviders for any p.models.includes(modelString)
 *      (handles canonical IDs passed directly). Returns canonicalModel=modelString.
 *   3. null — no provider found.
 *
 * @param {Map<string, import('./base.mjs').ProviderContractV1>} loadedProviders
 * @param {string} modelString
 * @returns {{ provider: import('./base.mjs').ProviderContractV1, name: string, canonicalModel: string }|null}
 */
export function getProviderForModel(loadedProviders, modelString) {
  // Step 1: alias resolution via models-registry.json
  const aliasEntry = _aliasMap.get(modelString);
  if (aliasEntry) {
    const { providerName, canonicalModel } = aliasEntry;
    const provider = loadedProviders.get(providerName);
    if (provider) {
      return { provider, name: providerName, canonicalModel };
    }
    // Alias exists but target provider is not loaded (not enabled) — fall through.
  }

  // Step 2: direct canonical lookup
  for (const [name, p] of loadedProviders) {
    if (p.models.includes(modelString)) {
      return { provider: p, name, canonicalModel: modelString };
    }
  }

  return null;
}

/**
 * Looks up a provider by name in the loaded Map. Returns null if not found.
 * Useful for tests that need to access a specific provider directly.
 *
 * @param {Map<string, import('./base.mjs').ProviderContractV1>} loadedProviders
 * @param {string} name
 * @returns {import('./base.mjs').ProviderContractV1|null}
 */
export function getProviderByName(loadedProviders, name) {
  return loadedProviders.get(name) ?? null;
}

/**
 * Returns all provider names in the static registry (whether enabled or not).
 * Used by /health and diagnostics.
 * At D4: returns ['anthropic']; at D6: returns ['anthropic', 'openai'];
 * at D8: returns ['anthropic', 'openai', 'mistral'].
 *
 * @returns {string[]}
 */
export function listAllProviderNames() {
  return STATIC_REGISTRY.map(p => p.name);
}