import { content } from "@deadhead/content";
import {
  effectiveStats,
  fuelPriceAt,
  type Contract as SimContract,
  type DispatchRecord,
  type FleetMember,
  type Resolution,
} from "@deadhead/sim";
import { z } from "zod";
import { logEntrySchema } from "./logbook";
import {
  contractSchema,
  idSchema,
  pilotModeSchema,
  pilotOrdersSchema,
  timeSchema,
} from "./entities";

/**
 * The save document (CR-014): everything the game database held, for the one
 * company on this device. Validated on every load and every save; each
 * `saveVersion` change ships with a migration (see `migrateSave`).
 */

const credits = z.number().int();
const activity = z.enum(["idle", "in-flight"]);

/** The sim's dispatch record, stored as it was created. */
export const dispatchRecordSchema = z.object({
  id: idSchema,
  shipId: idSchema,
  pilotId: idSchema,
  contract: contractSchema.nullable(),
  originId: idSchema,
  destinationId: idSchema,
  tutorial: z.boolean(),
  departureAt: timeSchema,
  arrivalAt: timeSchema,
  distanceMillionKm: z.number().nonnegative(),
  /** Fuel taken from the tank at departure (CR-015); 0 for tutorial runs and pre-tank trips. */
  fuelBurnedFu: z.number().nonnegative(),
  fuelCost: credits.nonnegative(),
  expectedPayout: credits,
  seed: z.number().int().nonnegative(),
});

/** A ship's tank (decision 0.5.94): fuel and its average purchase price. */
const tankSchema = z.object({
  fuelFu: z.number().nonnegative(),
  avgPrice: z.number().nonnegative(),
});

/** What resolving a dispatch did, kept for the "while you were away" summary. */
export const resolutionSchema = z.object({
  credits,
  /** Auto top-up on landing (decision 0.5.97). */
  topUp: z
    .object({
      locationId: idSchema,
      boughtFu: z.number().positive(),
      price: z.number().positive(),
      cost: credits.nonnegative(),
      tank: tankSchema,
    })
    .nullable(),
  pilotPay: credits.nonnegative(),
  loanRepayment: credits.nonnegative(),
  pilotXp: z.number().int().nonnegative(),
  shipLocationId: idSchema,
  discoversDestination: z.boolean(),
  pilotDutyHours: z.number().nonnegative(),
  pilotRestEndsAt: timeSchema.nullable(),
});

export const savedShipSchema = z.object({
  id: idSchema,
  modelId: idSchema,
  name: z.string().min(1),
  status: activity,
  /** Null while in flight. */
  locationId: idSchema.nullable(),
  /** Installed upgrade levels (CR-009); a missing upgrade is level 0. */
  upgrades: z.record(idSchema, z.number().int().positive()),
  /** In the upgrade shop until this time (decision 0.5.66); null or past: not. */
  inShopUntil: timeSchema.nullable(),
  /** The latest shop job, kept until the player has seen it. */
  shopUpgradeId: idSchema.nullable(),
  shopLevel: z.number().int().positive().nullable(),
  /**
   * The pilot aboard when the upgrade started, while they stay with the ship:
   * they come out rested (decision 0.5.135). Cleared when they leave it, and
   * when the shop time ends.
   */
  shopPilotId: idSchema.nullable(),
  /**
   * An upgrade's shop time hasn't been through catch-up yet: its end logs
   * "upgrade finished" (decision 0.5.141) and settles the shop rest.
   */
  shopOpen: z.boolean(),
  /** Handed over in the deal rather than bought (CR-013). */
  fromDeal: z.boolean(),
  createdAt: timeSchema,
  /** Its latest resolved arrival (the delivery time if none): picks the default Contracts location. */
  lastArrivalAt: timeSchema,
  /** Fuel on board, in fu (decision 0.5.94). */
  fuelFu: z.number().nonnegative(),
  /** Credits per fu, weighted by what was bought where (decision 0.5.98). */
  fuelAvgPrice: z.number().nonnegative(),
  /** Auto top-up on landing, or Manual (decision 0.5.97). */
  refuelPolicy: z.enum(["auto", "manual"]),
});

export const savedPilotSchema = z.object({
  id: idSchema,
  name: z.string().min(1),
  isAvatar: z.boolean(),
  isVeteran: z.boolean(),
  xp: z.number().int().nonnegative(),
  skills: z.record(idSchema, z.number().int().nonnegative()),
  skillPointsSpent: z.number().int().nonnegative(),
  assignedShipId: idSchema.nullable(),
  /** Only unassigned pilots store a location (decision 0.5.27). */
  locationId: idSchema.nullable(),
  status: activity,
  dutyHours: z.number().nonnegative(),
  restEndsAt: timeSchema.nullable(),
  createdAt: timeSchema,
  /** Manual or Independent, and orders (decision 0.5.124). */
  mode: pilotModeSchema,
  orders: pilotOrdersSchema,
  /** An Independent pilot's next decision point (CR-021 §2); null while flying or Manual. */
  nextDecisionAt: timeSchema.nullable(),
  /** Board periods in a row an Independent pilot found nothing to take (decision 0.5.128). */
  emptyPeriods: z.number().int().nonnegative(),
});

/** One ship-and-pilot pair's lasting capabilities (decision 0.5.115). */
export const fleetMemberSchema = z.object({
  modelId: idSchema,
  skills: z.record(idSchema, z.number().int().nonnegative()),
  upgrades: z.record(idSchema, z.number().int().positive()).optional(),
  fuelFu: z.number().nonnegative().optional(),
});

export const savedBoardSchema = z.object({
  id: idSchema,
  kind: z.enum(["location", "tutorial"]),
  locationId: idSchema,
  periodIndex: z.number().int(),
  /** Tutorial boards: runs completed when generated; 0 for location boards. */
  tutorialRun: z.number().int().nonnegative(),
  contracts: z.array(contractSchema),
  /**
   * Location boards: the qualifying fleet they were generated for (CR-019),
   * so a board can be reproduced. Null for tutorial and hand-made boards.
   */
  fleet: z.array(fleetMemberSchema).nullable(),
  createdAt: timeSchema,
});

export const savedDispatchSchema = z.object({
  id: idSchema,
  /** Null for a tutorial run (the loaner is not an owned ship). */
  shipId: idSchema.nullable(),
  pilotId: idSchema,
  tutorial: z.boolean(),
  /** Flown by an Independent pilot's own choice (CR-021): no notification, in the logbook. */
  independent: z.boolean(),
  record: dispatchRecordSchema,
  arrivalAt: timeSchema,
  status: z.enum(["in-flight", "resolved"]),
  resolution: resolutionSchema.nullable(),
  resolvedAt: timeSchema.nullable(),
  acknowledgedAt: timeSchema.nullable(),
});

/** The save version this build writes. Bump it with a new migration. */
export const CURRENT_SAVE_VERSION = 10;

export const saveDocumentSchema = z.object({
  saveVersion: z.literal(CURRENT_SAVE_VERSION),
  /** Identifies this company's save (debug info, notifications). */
  saveId: idSchema,
  /** The latest time the game has seen (decision 0.5.88): the clock never goes below it. */
  lastTimeSeen: timeSchema,
  player: z.object({
    /** 32-bit unsigned seed for boards, dispatches and names (decision 0.5.10). */
    worldSeed: z.number().int().nonnegative().max(0xffff_ffff),
    tutorialActive: z.boolean(),
    loanerLocationId: idSchema.nullable(),
    tutorialRunsCompleted: z.number().int().nonnegative(),
    dealAccepted: z.boolean(),
    createdAt: timeSchema,
    /** This company's welcome cards have been seen (decision 0.5.131). */
    welcomeSeen: z.boolean(),
    /**
     * When "While you were away" was last closed: the current absence runs
     * from here (decision 0.5.140).
     */
    awaySince: timeSchema,
    /** The absence the last closed pop-up covered, for the Logbook's "This absence". */
    lastAbsence: z.object({ from: timeSchema, to: timeSchema }).nullable(),
    /** Goals already logged as ready to claim, so each is logged once. */
    readyGoalsLogged: z.array(idSchema),
  }),
  company: z.object({
    id: idSchema,
    name: z.string().min(1),
    credits,
    loanBalance: credits.nonnegative(),
    /** The Dispatch Office is bought (decision 0.5.123). */
    dispatchOffice: z.boolean(),
    /** Credits Independent pilots never spend below (decision 0.5.127). */
    npcSpendingFloor: z.number().int().nonnegative(),
    /**
     * The player's last manual decision (decision 0.5.136): the fleet sleeps
     * `sleepAfterHours` later (0.5.137). Null only in a save just migrated to
     * version 9, until the engine first catches it up and sets it to that time.
     */
    lastManualDecisionAt: timeSchema.nullable(),
    /** Real hours without orders before the fleet goes quiet (Settings → Company). */
    sleepAfterHours: z.number().positive(),
  }),
  ships: z.array(savedShipSchema),
  pilots: z.array(savedPilotSchema),
  bays: z.array(z.object({ id: idSchema, locationId: idSchema, createdAt: timeSchema })),
  discoveredLocations: z.array(z.object({ locationId: idSchema, discoveredAt: timeSchema })),
  contractBoards: z.array(savedBoardSchema),
  dispatches: z.array(savedDispatchSchema),
  acceptedContracts: z.array(
    z.object({
      contractId: idSchema,
      periodIndex: z.number().int(),
      dispatchId: idSchema,
      acceptedAt: timeSchema,
    }),
  ),
  claimedGoals: z.array(z.object({ goalId: idSchema, claimedAt: timeSchema })),
  /**
   * Lifetime counts for goals, kept apart from `dispatches` so old resolved
   * dispatches can be pruned (CR-014 §2) without undoing progress.
   */
  stats: z.object({
    /** Contracts (not tutorial runs or deadheads) delivered. */
    contractDeliveries: z.number().int().nonnegative(),
    priorityDeliveries: z.number().int().nonnegative(),
  }),
  /** The last 7 days of what happened (decision 0.5.141), oldest first. */
  logbook: z.array(logEntrySchema),
});
export type SaveDocument = z.infer<typeof saveDocumentSchema>;

// The saved shapes are the sim's own: a change on either side fails the build.
type Same<A, B> = [A] extends [B] ? ([B] extends [A] ? true : false) : false;
const _sameContract: Same<z.infer<typeof contractSchema>, SimContract> = true;
const _sameRecord: Same<z.infer<typeof dispatchRecordSchema>, DispatchRecord> = true;
const _sameResolution: Same<z.infer<typeof resolutionSchema>, Resolution> = true;
const _sameFleetMember: Same<z.infer<typeof fleetMemberSchema>, FleetMember> = true;
void [_sameContract, _sameRecord, _sameResolution, _sameFleetMember];

/** One step: a save of version `from` to version `from + 1`. */
export interface SaveMigration {
  from: number;
  migrate(save: Record<string, unknown>): Record<string, unknown>;
}

type Doc = Record<string, unknown>;
const records = (value: unknown): Doc[] => (Array.isArray(value) ? (value as Doc[]) : []);

/**
 * Version 1 → 2 (CR-015 §5, fuel tanks): every ship gets a full tank, bought at
 * the price where it sits (the base price while in flight), on Auto top-up.
 * Earlier trips paid fuel in credits, so their records burned no tank fuel and
 * their resolutions had no top-up. Arrival times are untouched.
 */
function addFuelTanks(save: Doc): Doc {
  const { config } = content;
  const ships = records(save.ships).map((ship) => {
    const model = content.shipModel(String(ship.modelId));
    const upgrades = (ship.upgrades ?? {}) as Record<string, number>;
    const capacity = model ? effectiveStats(model, upgrades, content).tankCapacityFu : 0;
    const at = ship.locationId ? content.location(String(ship.locationId)) : undefined;
    return {
      ...ship,
      fuelFu: capacity,
      fuelAvgPrice: at ? fuelPriceAt(at, config) : config.baseFuelPricePerFu,
      refuelPolicy: "auto",
    };
  });
  const dispatches = records(save.dispatches).map((dispatch) => ({
    ...dispatch,
    record: { ...(dispatch.record as Doc), fuelBurnedFu: 0 },
    resolution: dispatch.resolution ? { ...(dispatch.resolution as Doc), topUp: null } : null,
  }));
  return { ...save, ships, dispatches };
}

/**
 * Version 2 → 3 (CR-018 §3): every ship goes to Manual refueling. Auto was the
 * default, not a choice; fuel, prices and credits are untouched.
 */
function manualRefueling(save: Doc): Doc {
  const ships = records(save.ships).map((ship) => ({ ...ship, refuelPolicy: "manual" }));
  return { ...save, ships };
}

/**
 * Every migration, in order: `from` → `from + 1`. A format change adds one
 * here and bumps `CURRENT_SAVE_VERSION`.
 */
/**
 * Version 3 → 4 (CR-019 §3): stored boards are dropped. They were made before
 * boards kept only jobs the fleet can complete, and regenerate on next view.
 */
function dropBoards(save: Doc): Doc {
  return { ...save, contractBoards: [] };
}

/**
 * Version 4 → 5 (CR-021 §3): every pilot Manual with default orders (home at
 * Earth, where the deal's bay is), no Dispatch Office, the default spending floor.
 */
function independentPilots(save: Doc): Doc {
  const orders = {
    destinationIds: null,
    cargoClassIds: content.cargoTypes.map((c) => c.id),
    takePriority: true,
    minProfit: 0,
    homeLocationId: content.config.deal.bayLocationId,
  };
  return {
    ...save,
    company: {
      ...(save.company as Doc),
      dispatchOffice: false,
      npcSpendingFloor: content.config.independentPilots.defaultSpendingFloor,
    },
    pilots: records(save.pilots).map((pilot) => ({
      ...pilot,
      mode: "manual",
      orders: { ...orders, cargoClassIds: [...orders.cargoClassIds] },
    })),
  };
}

/**
 * Version 5 → 6 (CR-021 Step 21.4): catch-up state. No pilot has a decision
 * pending or empty periods counted, and no dispatch was an Independent choice.
 */
function catchUpState(save: Doc): Doc {
  return {
    ...save,
    pilots: records(save.pilots).map((pilot) => ({
      ...pilot,
      nextDecisionAt: null,
      emptyPeriods: 0,
    })),
    dispatches: records(save.dispatches).map((dispatch) => ({ ...dispatch, independent: false })),
  };
}

/**
 * Version 6 → 7 (CR-022 §3): companies from before the welcome cards count as
 * having seen them, so nobody gets them mid-game.
 */
function welcomeSeen(save: Doc): Doc {
  return { ...save, player: { ...(save.player as Doc), welcomeSeen: true } };
}

/**
 * Version 7 → 8 (CR-023): no ship has a pilot waiting out the shop. An upgrade
 * already under way finishes as before, without the rest.
 */
function shopPilot(save: Doc): Doc {
  return {
    ...save,
    ships: records(save.ships).map((ship) => ({ ...ship, shopPilotId: null })),
  };
}

/**
 * Version 8 → 9 (CR-024): the default sleep threshold, and a last manual
 * decision the engine sets to the time it first opens the save (the migration
 * time, CR-024 §3), so nobody's fleet is asleep the moment they update.
 */
function fleetSleep(save: Doc): Doc {
  return {
    ...save,
    company: {
      ...(save.company as Doc),
      lastManualDecisionAt: null,
      sleepAfterHours: content.config.fleetSleep.defaultHours,
    },
  };
}

/**
 * Version 9 → 10 (CR-025 §4): the logbook. Resolved dispatches still in the
 * save become flight entries, with their top-ups, rests and discoveries;
 * level-ups can't be rebuilt and are dropped. An upgrade still showing in the
 * shop is left open, so catch-up logs its end. The absence runs from the last
 * time a summary was dismissed.
 */
function logbook(save: Doc): Doc {
  const entries: Doc[] = [];
  let seen = 0;
  for (const d of records(save.dispatches)) {
    const r = d.resolution as Doc | null;
    if (d.status !== "resolved" || !r) continue;
    const record = d.record as Doc;
    const contract = record.contract as Doc | null;
    const at = (d.resolvedAt as number | null) ?? (d.arrivalAt as number);
    if (typeof d.acknowledgedAt === "number") seen = Math.max(seen, d.acknowledgedAt);
    const who = { pilotId: d.pilotId, shipId: d.shipId ?? null };
    const pilotPay = r.pilotPay as number;
    const loanRepayment = r.loanRepayment as number;
    entries.push({
      id: `${d.id}:flight`,
      at,
      ...who,
      kind: "flight",
      dispatchId: d.id,
      deadhead: contract === null,
      tutorial: d.tutorial,
      independent: d.independent,
      originId: record.originId,
      destinationId: record.destinationId,
      goodId: contract?.goodId ?? null,
      massTonnes: contract?.massTonnes ?? null,
      shipper: contract?.shipper ?? null,
      payout: Math.max(0, (r.credits as number) + pilotPay + loanRepayment),
      pilotPay,
      fuelCost: record.fuelCost,
      loanRepayment,
      xp: r.pilotXp,
      scriptedId: contract?.scriptedId ?? null,
    });
    const topUp = r.topUp as Doc | null;
    if (topUp && (topUp.boughtFu as number) > 0) {
      entries.push({
        id: `${d.id}:top-up`,
        at,
        ...who,
        kind: "refuel",
        locationId: topUp.locationId,
        boughtFu: topUp.boughtFu,
        cost: topUp.cost,
        source: "top-up",
      });
    }
    if (typeof r.pilotRestEndsAt === "number") {
      entries.push({ id: `${d.id}:rest`, at, ...who, kind: "rest", until: r.pilotRestEndsAt });
    }
    if (r.discoversDestination) {
      entries.push({
        id: `${d.id}:discovery`,
        at,
        ...who,
        kind: "discovery",
        locationId: record.destinationId,
      });
    }
  }
  entries.sort((a, b) => (a.at as number) - (b.at as number));
  const player = save.player as Doc;
  return {
    ...save,
    player: {
      ...player,
      awaySince: seen > 0 ? seen : player.createdAt,
      lastAbsence: null,
      readyGoalsLogged: [],
    },
    ships: records(save.ships).map((ship) => ({
      ...ship,
      shopOpen: ship.inShopUntil !== null && ship.shopUpgradeId !== null,
    })),
    logbook: entries,
  };
}

export const SAVE_MIGRATIONS: readonly SaveMigration[] = [
  { from: 1, migrate: addFuelTanks },
  { from: 2, migrate: manualRefueling },
  { from: 3, migrate: dropBoards },
  { from: 4, migrate: independentPilots },
  { from: 5, migrate: catchUpState },
  { from: 6, migrate: welcomeSeen },
  { from: 7, migrate: shopPilot },
  { from: 8, migrate: fleetSleep },
  { from: 9, migrate: logbook },
];

export type SaveParse = { ok: true; save: SaveDocument } | { ok: false; error: string };
type Stepped = { ok: true; save: Record<string, unknown> } | { ok: false; error: string };

/**
 * Steps a save from its version up to `current`, one migration at a time.
 * Doesn't validate the result; `migrateSave` does.
 */
export function applyMigrations(
  raw: unknown,
  migrations: readonly SaveMigration[],
  current: number,
): Stepped {
  if (typeof raw !== "object" || raw === null || Array.isArray(raw)) {
    return { ok: false, error: "The save isn't a save document." };
  }
  let save = raw as Record<string, unknown>;
  let version = save.saveVersion;
  if (typeof version !== "number" || !Number.isInteger(version) || version < 1) {
    return { ok: false, error: "The save has no valid saveVersion." };
  }
  if (version > current) {
    return {
      ok: false,
      error: `The save is from a newer version of the game (save version ${version}, this build reads up to ${current}).`,
    };
  }
  while (version < current) {
    const step = migrations.find((m) => m.from === version);
    if (!step) return { ok: false, error: `No migration from save version ${version}.` };
    save = { ...step.migrate(save), saveVersion: version + 1 };
    version += 1;
  }
  return { ok: true, save };
}

/**
 * Migrates a save of any known version to the current one and validates it.
 * Never throws: an unknown or broken save gives a readable error.
 */
export function migrateSave(raw: unknown): SaveParse {
  const stepped = applyMigrations(raw, SAVE_MIGRATIONS, CURRENT_SAVE_VERSION);
  if (!stepped.ok) return stepped;
  const parsed = saveDocumentSchema.safeParse(stepped.save);
  return parsed.success
    ? { ok: true, save: parsed.data }
    : {
        ok: false,
        error: `The save is damaged:
${z.prettifyError(parsed.error)}`,
      };
}