/**
 * Advanced search syntax (spec §30). Browser-safe.
 *
 *   openai pricing entity:org_openai type:pricing_change,terms_change after:2026-09-01 before:2026-09-10
 *   silent:true first_party:true confirmed:true importance:>70 confidence:>=50 signal:>80
 *   source:openai category:ai country:CA lang:fr class:pricing group:security cluster:clu_…
 *
 * Quoted values are supported: source:"bank of canada". Unknown keys stay in the free-text part.
 */
export interface ParsedSearch {
  text: string;
  filters: {
    entity?: string;
    source?: string;
    domain?: string;
    event_type?: string;
    group?: string;
    category?: string;
    country?: string;
    language?: string;
    after?: string;
    before?: string;
    silent_change?: boolean;
    first_party?: boolean;
    confirmed?: boolean;
    importance_min?: number;
    confidence_min?: number;
    signal_min?: number;
    change_class?: string;
    cluster?: string;
    sensor?: string;
    url?: string;
  };
  tokens: { key: string; value: string }[];
}

const KEYS = new Set(["entity", "source", "domain", "type", "event_type", "group", "category", "cat", "country", "lang", "language", "after", "since", "before", "until", "silent", "first_party", "firstparty", "confirmed", "importance", "imp", "confidence", "conf", "signal", "class", "cluster", "sensor", "url", "is"]);

function bool(v: string): boolean | undefined {
  const s = v.toLowerCase();
  if (["true", "1", "yes", "y"].includes(s)) return true;
  if (["false", "0", "no", "n"].includes(s)) return false;
  return undefined;
}

function num(v: string): number | undefined {
  const m = v.match(/^(?:>=|>|=)?\s*(\d+(?:\.\d+)?)$/);
  return m ? Number(m[1]) : undefined;
}

/** Relative dates: 1h, 6h, 24h, 7d, 30d → ISO timestamp. */
function date(v: string): string | undefined {
  const rel = v.match(/^(\d+)\s*([hdwm])$/i);
  if (rel) {
    const n = Number(rel[1]);
    const unit = rel[2]!.toLowerCase();
    const ms = unit === "h" ? 3600e3 : unit === "d" ? 86400e3 : unit === "w" ? 7 * 86400e3 : 30 * 86400e3;
    return new Date(Date.now() - n * ms).toISOString();
  }
  const d = new Date(v.length === 10 ? `${v}T00:00:00Z` : v);
  return Number.isNaN(d.getTime()) ? undefined : d.toISOString();
}

export function parseSearch(input: string): ParsedSearch {
  const tokens: { key: string; value: string }[] = [];
  const free: string[] = [];
  const re = /(\w+):("([^"]*)"|'([^']*)'|(\S+))|("([^"]*)")|(\S+)/g;
  let m: RegExpExecArray | null;
  while ((m = re.exec(input)) !== null) {
    if (m[1] && KEYS.has(m[1].toLowerCase())) tokens.push({ key: m[1].toLowerCase(), value: (m[3] ?? m[4] ?? m[5] ?? "").trim() });
    else free.push(m[7] ?? m[8] ?? m[0]);
  }
  const f: ParsedSearch["filters"] = {};
  for (const { key, value } of tokens) {
    switch (key) {
      case "entity":
        f.entity = /^(org|prd|ent)_/.test(value) ? value : `org_${value.toLowerCase().replace(/[^a-z0-9]+/g, "-")}`;
        break;
      case "source":
        f.source = value.toLowerCase().replace(/[^a-z0-9.-]+/g, "-");
        break;
      case "domain":
        f.domain = value.toLowerCase();
        break;
      case "type":
      case "event_type":
        f.event_type = value;
        break;
      case "group":
        f.group = value.toLowerCase();
        break;
      case "category":
      case "cat":
        f.category = value.toLowerCase();
        break;
      case "country":
        f.country = value.toUpperCase();
        break;
      case "lang":
      case "language":
        f.language = value.toLowerCase();
        break;
      case "after":
      case "since":
        f.after = date(value);
        break;
      case "before":
      case "until":
        f.before = date(value);
        break;
      case "silent":
        f.silent_change = bool(value);
        break;
      case "first_party":
      case "firstparty":
        f.first_party = bool(value);
        break;
      case "confirmed":
        f.confirmed = bool(value);
        break;
      case "importance":
      case "imp":
        f.importance_min = num(value);
        break;
      case "confidence":
      case "conf":
        f.confidence_min = num(value);
        break;
      case "signal":
        f.signal_min = num(value);
        break;
      case "class":
        f.change_class = value.toLowerCase();
        break;
      case "cluster":
        f.cluster = value;
        break;
      case "sensor":
        f.sensor = value;
        break;
      case "url":
        f.url = value;
        break;
      case "is":
        if (value === "silent") f.silent_change = true;
        else if (value === "breaking") f.importance_min = Math.max(f.importance_min ?? 0, 80);
        else if (value === "confirmed") f.confirmed = true;
        else if (value === "first-party" || value === "firstparty") f.first_party = true;
        break;
    }
  }
  return { text: free.join(" ").trim(), filters: f, tokens };
}

/** Inverse: build a query string from filters (for saved views / URL sync). */
export function stringifySearch(p: { text?: string; filters: ParsedSearch["filters"] }): string {
  const parts: string[] = [];
  if (p.text) parts.push(p.text);
  const f = p.filters;
  const q = (v: string): string => (/\s/.test(v) ? `"${v}"` : v);
  if (f.entity) parts.push(`entity:${q(f.entity)}`);
  if (f.source) parts.push(`source:${q(f.source)}`);
  if (f.domain) parts.push(`domain:${f.domain}`);
  if (f.event_type) parts.push(`type:${f.event_type}`);
  if (f.group) parts.push(`group:${f.group}`);
  if (f.category) parts.push(`category:${f.category}`);
  if (f.country) parts.push(`country:${f.country}`);
  if (f.language) parts.push(`lang:${f.language}`);
  if (f.after) parts.push(`after:${f.after.slice(0, 10)}`);
  if (f.before) parts.push(`before:${f.before.slice(0, 10)}`);
  if (f.silent_change !== undefined) parts.push(`silent:${f.silent_change}`);
  if (f.first_party !== undefined) parts.push(`first_party:${f.first_party}`);
  if (f.confirmed !== undefined) parts.push(`confirmed:${f.confirmed}`);
  if (f.importance_min !== undefined) parts.push(`importance:>${f.importance_min}`);
  if (f.confidence_min !== undefined) parts.push(`confidence:>${f.confidence_min}`);
  if (f.signal_min !== undefined) parts.push(`signal:>${f.signal_min}`);
  if (f.change_class) parts.push(`class:${f.change_class}`);
  if (f.cluster) parts.push(`cluster:${f.cluster}`);
  return parts.join(" ");
}