/**
 * The contract.
 *
 * Almost all of this comes straight from the Hub, which is CORS-open. The app has
 * two endpoints of its own: `POST /api/train` to start a run, and
 * `POST /api/preflight` to measure a dataset — the one read that needs the model's
 * real tokenizer and chat template. See `src/hub.ts` for where each shape is
 * filled in.
 *
 * A rule that shapes this file: the user has never trained a model and never
 * will read a docs page. Nothing here is measured in tokens, steps or anything
 * else they'd have to look up — budgets are minutes and conversation counts, and
 * the only structural concept that ever surfaces is "this conversation is too
 * long and loses its ending", and only when it actually happens.
 */

/* -------------------------------------------------------------------------- */
/* Account                                                                    */
/* -------------------------------------------------------------------------- */

export interface HfUser {
  /** Hub username, and the namespace the trained model lands in. */
  name: string;
  /**
   * Whether the account has a way to pay. Jobs are pay-as-you-go on the user's
   * own credit, so without this nothing can run — and it's worth knowing that
   * before they've picked anything, not after.
   */
  canPay: boolean;
}

/* -------------------------------------------------------------------------- */
/* Recipes                                                                    */
/* -------------------------------------------------------------------------- */

/** One of three curated models. Hyperparameters are never exposed. */
export interface Model {
  /** The Hub id, which is also what `POST /api/train` takes. */
  id: string;
  /** "Qwen3 4B" */
  label: string;
  /** One short line on what picking this one gets you. */
  note: string;
  /** Exactly one model is flagged; it's preselected. */
  recommended: boolean;
}

export type PlanId = "quick" | "balanced" | "full";

/**
 * How much to train on. The only dial the user touches.
 *
 * Just a label here: the budget itself is a token count that lives in
 * PLAN_TOKENS in server/app.py, because turning it into a number of
 * conversations needs the dataset measured with a real tokenizer.
 */
export interface Plan {
  id: PlanId;
  /** "Quick" */
  label: string;
}

/* -------------------------------------------------------------------------- */
/* Datasets                                                                   */
/* -------------------------------------------------------------------------- */

/**
 * Where a dataset came from. Used only for ordering and the example badge —
 * there are no tabs, everything lives in one list.
 */
export type DatasetSource = "example" | "yours" | "hub";

export interface DatasetSummary {
  /** "qgallouedec/my-chats" */
  id: string;
  private: boolean;
  /** Gated datasets need terms accepted before the job can read them. */
  gated: boolean;
  rows: number;
  description: string;
  source: DatasetSource;
  /**
   * What the dataset's own card claims about having a `messages` column.
   *
   *   "chat"    — it declares one, so it can be trained on
   *   "other"   — it declares its columns and `messages` isn't among them, which
   *               is the one reliable *negative*: it really can't be trained on
   *   "unknown" — the card says nothing about its columns
   *
   * "unknown" used to be lumped in with "other" and hidden, which was wrong and
   * badly so: of 30 datasets under one real account, 28 declare nothing at all, so
   * searching your own name returned "nothing usable matched". A card is a weak
   * signal — plenty of perfectly good datasets never write one — and preflight,
   * which reads actual rows through the viewer, is the real authority. So unknown
   * datasets are listed and selectable, and the Check step decides.
   */
  format: "chat" | "other" | "unknown";
}

/* -------------------------------------------------------------------------- */
/* Preflight                                                                  */
/* -------------------------------------------------------------------------- */

/**
 * `tool` appears in tool-calling datasets: it's the turn carrying what a tool
 * returned, which the model reads but is not trained to produce.
 */
export type Role = "system" | "user" | "assistant" | "tool";

/**
 * One call the assistant is being taught to make. `arguments` arrives with values
 * already flattened to strings — the server does that so this side only lays them
 * out, and so a nested object reads as compact JSON rather than "[object Object]".
 */
export interface ToolCall {
  name: string;
  arguments: Record<string, string>;
}

export interface Message {
  role: Role;
  content: string;
  /** Set on an assistant turn that calls tools instead of writing a reply. */
  toolCalls?: ToolCall[];
  /** On a `tool` turn, which tool produced it. */
  name?: string;
}

/**
 * One conversation, shown to the user as a conversation.
 *
 * If the length limit falls inside it, `cutFromMessage` marks the first turn
 * that gets lost so the preview can fade out at exactly that point. Both cut
 * fields are null whenever the conversation fits, which is the common case —
 * the idea of a limit never appears unless it actually bites.
 */
export interface PreviewSample {
  messages: Message[];
  cutFromMessage: number | null;
  /** If the cut lands mid-message, how many characters of it survive. */
  cutAtChar: number | null;
}

export type IssueLevel = "error" | "warning" | "info";

/** A preflight finding, phrased for someone who has never trained a model. */
export interface Issue {
  level: IssueLevel;
  title: string;
  detail: string;
}

/** What one plan works out to for this dataset. */
export interface PlanEstimate {
  planId: PlanId;
  conversations: number;
  estMinutes: number;
  /** What it costs on the user's own account, at the flavor's hourly rate. */
  estCostUsd: number;
}

export interface PreflightReport {
  datasetId: string;
  totalRows: number;
  /** Conversations that lose their ending at the shared length limit. */
  truncatedCount: number;
  /** Same, as a share of the sample, 0..1. */
  truncatedPct: number;
  issues: Issue[];
  samples: PreviewSample[];
  perPlan: Record<PlanId, PlanEstimate>;
  recommendedPlan: PlanId;
}

/* -------------------------------------------------------------------------- */
/* Runs                                                                       */
/* -------------------------------------------------------------------------- */

/**
 * The stages a run moves through. The first three come from the Hub's own job
 * stage; the rest are the recipe announcing itself on stdout, which the log
 * stream carries back. See `[fts] stage` in server/recipe/train.py.
 */
export type RunStatus =
  | "queued"
  | "starting"
  | "training"
  | "sampling"
  | "pushing"
  | "done"
  | "error";

export interface LogLine {
  text: string;
  level: "info" | "warn" | "error";
}

/** Base vs tuned on the same prompt, taken from conversations held back from training. */
export interface SampleComparison {
  prompt: string;
  before: string;
  after: string;
}

export interface Run {
  /** The HF Jobs job id — the id every Hub jobs endpoint takes. */
  id: string;
  status: RunStatus;
  modelId: string;
  planId: PlanId;
  datasetId: string;
  /** Destination repo in the user's namespace. */
  outputRepo: string;
  createdAt: string;
  /** Overall completion, 0..1. The user never sees a step count. */
  progress: number;
  /** Technical detail, available behind a disclosure but never surfaced by default. */
  logs: LogLine[];
  /** Seconds remaining, or null when we can't say. */
  etaSeconds: number | null;
  /** Populated once status reaches "done" and the samples file has been read. */
  samples?: SampleComparison[];
  error?: string;
}

/** Anything that hasn't finished — what the header lists. */
export function isActive(run: Run) {
  return run.status !== "done" && run.status !== "error";
}