// Live seed interview — per-turn handler.
//
// Stateless on the server: the client passes the running thread + the draft
// extracted so far, plus the user's latest reply. We call the LLM with the
// character + interview prompts and get back { assistant turn, updated draft,
// confidence, ready }.

import "server-only";
import { defaultGateway, chatJSON, type Message } from "./gateway";
import { loadPrompt } from "./prompts";

export interface SeedDraft {
  title: string;
  problem: string;
  targetUser: string;
  desiredOutcome: string;
  initialHypothesis?: string;
  constraints?: string[];
}

export interface InterviewTurn {
  role: "socrates" | "user";
  text: string;
}

export interface InterviewStepArgs {
  /** Running interview history. Empty array on the first call → Socrates opens. */
  history: InterviewTurn[];
  /** Latest user reply (empty string for the opening turn). */
  userText: string;
  /** Draft extracted so far. Empty on the first call. */
  draft: SeedDraft;
}

export interface InterviewStepResult {
  text: string;
  draft: SeedDraft;
  confidence: number;
  ready: boolean;
  inputTokens: number;
  outputTokens: number;
  provider: string;
  model: string;
}

const interviewJsonSchema = {
  type: "object",
  additionalProperties: false,
  required: ["text", "draft", "confidence", "ready"],
  properties: {
    text: { type: "string", minLength: 1 },
    draft: {
      type: "object",
      additionalProperties: false,
      required: ["title", "problem", "targetUser", "desiredOutcome"],
      properties: {
        title: { type: "string" },
        problem: { type: "string" },
        targetUser: { type: "string" },
        desiredOutcome: { type: "string" },
        initialHypothesis: { type: "string" },
        constraints: { type: "array", items: { type: "string" } },
      },
    },
    confidence: { type: "number", minimum: 0, maximum: 1 },
    ready: { type: "boolean" },
  },
} as const;

interface RawResponse {
  text?: string;
  draft?: Partial<SeedDraft>;
  confidence?: number;
  ready?: boolean;
}

export async function interviewStep(args: InterviewStepArgs): Promise<InterviewStepResult> {
  const character = loadPrompt("socrates/character.md");
  const interview = loadPrompt("socrates/interview.md");

  const userTurnsSoFar = args.history.filter(t => t.role === "user").length;
  const remaining = Math.max(0, 5 - userTurnsSoFar - (args.userText.trim().length > 0 ? 1 : 0));

  const messages: Message[] = [
    {
      role: "system",
      content: [
        character,
        "---",
        interview,
        "---",
        `Draft so far (your previous extraction):\n\`\`\`json\n${JSON.stringify(args.draft, null, 2)}\n\`\`\``,
        `Turns remaining before ready signal becomes mandatory: ${remaining}`,
      ].join("\n\n"),
    },
  ];

  // Replay history so the LLM has full context.
  for (const t of args.history) {
    messages.push({ role: t.role === "socrates" ? "assistant" : "user", content: t.text });
  }
  if (args.userText.trim().length > 0) {
    messages.push({ role: "user", content: args.userText });
  } else if (args.history.length === 0) {
    messages.push({ role: "user", content: "Begin the interview." });
  }

  const gateway = defaultGateway();
  const { value, result } = await chatJSON<RawResponse>(gateway, messages, {
    temperature: 0.4,
    maxTokens: 768,
    jsonSchema: { name: "interview_step", schema: interviewJsonSchema as Record<string, unknown> },
    jsonObjectMode: true,
    maxRepairs: 2,
  });

  // Normalize / merge — the LLM may emit a partial draft; we union with the
  // prior draft so a user backtracking doesn't wipe a previously-confirmed field.
  const incoming: Partial<SeedDraft> = value?.draft ?? {};
  const draft: SeedDraft = {
    title: nonEmpty(incoming.title) ?? args.draft.title ?? "",
    problem: nonEmpty(incoming.problem) ?? args.draft.problem ?? "",
    targetUser: nonEmpty(incoming.targetUser) ?? args.draft.targetUser ?? "",
    desiredOutcome: nonEmpty(incoming.desiredOutcome) ?? args.draft.desiredOutcome ?? "",
    initialHypothesis: nonEmpty(incoming.initialHypothesis) ?? args.draft.initialHypothesis,
    constraints: Array.isArray(incoming.constraints) ? incoming.constraints : args.draft.constraints,
  };

  return {
    text: typeof value?.text === "string" && value.text.length > 0 ? value.text : "[empty response]",
    draft,
    confidence: clamp01(value?.confidence ?? 0),
    ready: !!value?.ready,
    inputTokens: result.inputTokens,
    outputTokens: result.outputTokens,
    provider: gateway.provider,
    model: gateway.model,
  };
}

function nonEmpty(s: unknown): string | undefined {
  if (typeof s !== "string") return undefined;
  const t = s.trim();
  return t.length > 0 ? t : undefined;
}

function clamp01(n: number): number {
  if (Number.isNaN(n)) return 0;
  return Math.max(0, Math.min(1, n));
}