gemini-compat-endpoint

import fs from "fs";
import path from "path";

// ============================================================================
// State Types (based on standalone_generator_guide/src/media-promotion-core/state.ts)
// ============================================================================

/**
 * BREAKING CHANGE (2025-12):
 * - filename is now optional (we no longer copy originals to chat WD)
 * - originAbs is the SSOT for i2i resolution
 * - preview naming: preview-<origin> instead of analysis-<stem>.jpg
 */
export type AttachmentItem = {
  filename?: string;     // optional - we may not keep 1:1 copies
  origin?: string;       // LM Studio fileIdentifier (e.g., "1766017090130 - 411.jpg")
  originAbs?: string;    // absolute path in user-files (SSOT for i2i!)
  originalName?: string; // real original filename from LM Studio metadata (for labels)
  preview?: string;      // relative JPEG preview (only for promoted/base64-injected attachments)
  createdAt: string;     // ISO timestamp
  n: number;             // 1-based stable attachment counter - NEVER CHANGES!
};

export type VariantItem = {
  filename: string;      // relative original (PNG/JPG/WEBP)
  preview: string;       // relative JPEG preview
  originAbs?: string;    // absolute path to original (for Files API promotion)
  createdAt: string;     // ISO timestamp
  v: number;             // 1-based variant index within generation batch
};

export type ChatMediaState = {
  attachments: AttachmentItem[];     // max 2
  variants: VariantItem[];           // max 3 (Pro) or max 1 (Flash)
  lastEvent?: { type: "attachment" | "variants"; at: string };
  counters: { nextAttachmentN?: number; nextVariantV?: number };
  // Idempotency tracking for vision promotion
  injectedMarkdown?: string[];         // Track injected image basenames to prevent duplicates
  lastVariantsTs?: string;             // Latest generated-image <ts> group observed
  lastPromotedTs?: string;             // Latest generated-image <ts> group already promoted
  lastPromotedAttachmentN?: number;    // Latest attachment n already promoted
};

const FILE_NAME = "chat_media_state.json";

// ============================================================================
// Timestamp helper
// ============================================================================

export function tsForFilename(d = new Date()): string {
  const year = d.getUTCFullYear();
  const month = String(d.getUTCMonth() + 1).padStart(2, "0");
  const day = String(d.getUTCDate()).padStart(2, "0");
  const hours = String(d.getUTCHours()).padStart(2, "0");
  const minutes = String(d.getUTCMinutes()).padStart(2, "0");
  const seconds = String(d.getUTCSeconds()).padStart(2, "0");
  const millis = String(d.getUTCMilliseconds()).padStart(3, "0");
  return `${year}${month}${day}T${hours}${minutes}${seconds}${millis}Z`;
}

// ============================================================================
// Read/Write with atomic writes
// ============================================================================

export async function readChatMediaState(chatWd: string): Promise<ChatMediaState> {
  const p = path.join(chatWd, FILE_NAME);
  try {
    const raw = await fs.promises.readFile(p, "utf8");
    const parsed = JSON.parse(raw);
    return normalizeState(parsed);
  } catch {
    return { attachments: [], variants: [], counters: {} };
  }
}

function normalizeState(s: any): ChatMediaState {
  return {
    attachments: Array.isArray(s?.attachments) ? s.attachments : [],
    variants: Array.isArray(s?.variants) ? s.variants : [],
    lastEvent: s?.lastEvent,
    counters: typeof s?.counters === "object" && s?.counters ? s.counters : {},
    injectedMarkdown: Array.isArray(s?.injectedMarkdown) ? s.injectedMarkdown : undefined,
    lastVariantsTs: typeof s?.lastVariantsTs === "string" ? s.lastVariantsTs : undefined,
    lastPromotedTs: typeof s?.lastPromotedTs === "string" ? s.lastPromotedTs : undefined,
    lastPromotedAttachmentN: typeof s?.lastPromotedAttachmentN === "number" ? s.lastPromotedAttachmentN : undefined,
  };
}

/**
 * Atomic write: write to tmp file then rename to prevent corruption
 */
export async function writeChatMediaStateAtomic(chatWd: string, state: ChatMediaState): Promise<void> {
  await fs.promises.mkdir(chatWd, { recursive: true });
  const tmp = path.join(chatWd, `${FILE_NAME}.tmp`);
  const dst = path.join(chatWd, FILE_NAME);
  const json = JSON.stringify(state, null, 2);
  await fs.promises.writeFile(tmp, json, "utf8");
  await fs.promises.rename(tmp, dst);
}

/** @deprecated Use writeChatMediaStateAtomic instead */
export async function writeChatMediaState(chatWd: string, state: ChatMediaState): Promise<void> {
  return writeChatMediaStateAtomic(chatWd, state);
}

// ============================================================================
// Legacy record functions (kept for backwards compatibility)
// For new code, use importAttachmentBatch from attachments.ts instead
// ============================================================================

/** @deprecated Use importAttachmentBatch instead */
export async function recordAttachmentsProvision(chatWd: string, attachments: Array<{ filename?: string; origin?: string; originAbs?: string; originalName?: string; preview?: string; createdAt?: string }>): Promise<ChatMediaState> {
  const state = await readChatMediaState(chatWd);
  const list: AttachmentItem[] = attachments.map((a, idx) => ({
    filename: a.filename,
    origin: a.origin,
    originAbs: a.originAbs,
    originalName: a.originalName,
    preview: a.preview,
    createdAt: a.createdAt ?? new Date().toISOString(),
    n: idx + 1, // WARNING: This is wrong! Use importAttachmentBatch for stable n
  }));
  const nextState: ChatMediaState = {
    ...state,
    attachments: list,
    lastEvent: { type: "attachment", at: new Date().toISOString() },
    counters: { ...(state.counters ?? {}), nextAttachmentN: list.length + 1, nextVariantV: 1 },
  };
  await writeChatMediaStateAtomic(chatWd, nextState);
  return nextState;
}

/** @deprecated Use importAttachmentBatch instead */
export async function recordAttachmentProvision(chatWd: string, params: { filename?: string; origin?: string; originAbs?: string; originalName?: string; preview?: string; createdAt?: string }): Promise<ChatMediaState> {
  return recordAttachmentsProvision(chatWd, [params]);
}

export async function recordVariantsProvision(chatWd: string, variants: Array<{ filename: string; preview: string; createdAt?: string }>): Promise<ChatMediaState> {
  const state = await readChatMediaState(chatWd);
  const list: VariantItem[] = variants.map((v, idx) => ({
    filename: v.filename,
    preview: v.preview,
    originAbs: (v as any).originAbs,
    createdAt: v.createdAt ?? new Date().toISOString(),
    v: (v as any).v ?? (idx + 1),
  }));
  const nextState: ChatMediaState = {
    ...state,
    variants: list,
    lastEvent: { type: "variants", at: new Date().toISOString() },
    counters: { ...(state.counters ?? {}), nextVariantV: list.length + 1 },
  };
  await writeChatMediaStateAtomic(chatWd, nextState);
  return nextState;
}