export type NpcDialogueKind =
  "firm" | "lowball" | "backward" | "stall" | "concede" | "good" | "overpay" | "closed" | "accept";

type DialogueLine = (amount: string, asking: string) => string;

const LINES: Record<NpcDialogueKind, DialogueLine[]> = {
  firm: [
    (amount) => `I'm not going any lower than ${amount}. Take it or leave it.`,
    (amount) => `That's my final price — ${amount}. I've got other buyers knocking.`,
    (amount) => `I'm holding at ${amount}. My prices are already fair.`,
  ],
  lowball: [
    (amount) => `That's an insult! I'll come down to ${amount} — not a fraction less.`,
    (amount) => `You're joking, right? ${amount} and not a fraction less.`,
    (amount) => `I paid more than that for lunch! ${amount} — final offer.`,
  ],
  backward: [
    (amount) => `Now you're offering less than before? I'm holding firm at ${amount}.`,
    (amount) => `We were making progress and now this? I'm staying at ${amount}.`,
  ],
  stall: [
    () => "Really? That's hardly different. Negotiate like you mean it.",
    () => "That tiny increase isn't negotiating. Come back with a real number.",
    () => "You're just inching up now. Bring something meaningful.",
  ],
  concede: [
    (amount) => `Hmm, not sure about that... how about ${amount}?`,
    (amount) => `I could stretch to ${amount}... if we're serious about this.`,
    (amount) => `Let's not waste each other's time — ${amount}.`,
    (amount) => `Alright, I'll bend a little. ${amount}?`,
  ],
  good: [
    () => "Now we're talking. That's a fair price — you've got a deal.",
    () => "You drive a hard bargain, but that's a price I can live with.",
    () => "That works for me. A man's gotta make a living, after all.",
  ],
  overpay: [
    () => "Wait — more than I asked? Sold! You won't regret it.",
    () => "Generous! I'd have taken less, but I won't argue. It's yours.",
    () => "Whoa, okay! Not going to talk you out of that one. Done deal.",
  ],
  closed: [
    (_amount, asking) => `Alright, that's enough haggling. Buy it at ${asking} or not at all.`,
    (_amount, asking) => `I'm done negotiating. The price is ${asking} — take it or leave it.`,
  ],
  accept: [
    () => "I think that price is acceptable. Let's shake on it.",
    () => "Done. Pleasure doing business with you.",
    () => "Deal! Good doing business with you.",
  ],
};

/**
 * Vendor flavour lines for the in-dialog chat. Amounts are formatted plain.
 * Pass a custom `rng` (0–1) for deterministic output; otherwise a line is
 * picked at random each call.
 */
export function npcDialogue(
  kind: NpcDialogueKind,
  amount?: number,
  asking?: number,
  rng: () => number = Math.random,
): string {
  const lines = LINES[kind];
  const index = Math.min(lines.length - 1, Math.max(0, Math.floor(rng() * lines.length)));
  return lines[index]((amount ?? 0).toLocaleString(), (asking ?? 0).toLocaleString());
}