const fs = require('fs')
const path = require('path')

const db = require('./shardAssets.db')
const atlasDb = require('../shardAtlas/shardAtlas.db')
const core = require('../../core')
const bridge = require('../../utils/assetBridge')
const uoLinkConfig = require('../uoLinkConfig/uoLinkConfig.model')
const log = require('../../core').logger('shardAssets')

// Client artwork, over the bridge (docs/link/v8.md — protocol 8, phase 3).
//
// What this replaces: until now the only way a creature got a picture on this
// site was for an operator to open UOFiddler on a desktop, export sprites by
// hand, copy them to the web host and write a `spawnAtlas.art.json` naming each
// one. Almost nobody did, so `shard_spawn_creatures.art` was NULL on every
// install and the atlas rendered as text.
//
// The shard has had those files the whole time — a ServUO server cannot boot
// without a UO client — so as of protocol 8 it decodes them itself and hands the
// pictures over the same request/reply path as every other shard read.
//
// ── Two passes, and they answer different questions ───────────────────
//
// **The catalogue** (§4.8, §11) is one thumbnail per creature body: the shard
// walks bodies 0–2047, validates each index entry, decodes the ones that are real
// and hands back `{ key, sha256 }` first and the PNG second. On a stock client
// that is **787 sprites**, not the 1,144 the decoder claims — see below.
//
// **Body resolution** (§8) is the join. The atlas knows a creature by the class
// name in `Spawns/*.xml`; the client knows it by a body id; nothing in the ServUO
// tree declares the mapping. Only code inside ServUO can answer it, by
// constructing the creature and reading `Body.BodyID`, and that is the whole
// reason this could not be done off the shard.
//
// ── The 357, and why nothing here trusts a success ────────────────────
//
// 357 of the bodies ServUO's decoder returns a bitmap for **have no art**. Their
// index entry reads `length 0`, the library's stream buffer still holds the
// previous creature, and what comes back is whichever body was decoded before —
// a real, plausible, correctly-sized picture of the wrong animal. The shard now
// validates every index entry before it decodes, which is what cut the catalogue
// from 1,144 to 787, and the count going down is the point.
//
// The consequence for this file is a rule: **a missing asset is a normal
// outcome, never an error.** Two thirds of the player bodies have no art on a
// stock client (§5.2), so an import that reported eight failures every time would
// teach an operator to ignore the panel.
//
// ── Where the pictures go, and what still wins ────────────────────────
//
// Into `<uploads>/atlas/`, through the same door the operator's own artwork uses,
// and `shard_spawn_creatures.art` is DERIVED from them rather than written by
// them. **The operator's `spawnAtlas.art.json` still wins outright**: someone who
// has drawn their own creature portraits must not have them replaced by a sprite
// rip on the next Update.
//
// ── Why the resolution does not live on the atlas row ─────────────────
//
// `shard_spawn_creatures` is emptied and refilled on every atlas refresh. A body
// id or a filename stored there would be destroyed by an ordinary re-parse of the
// ServUO tree, and the next asset Update would find the client files unchanged,
// report "nothing to do" and never restore it. So both live in their own tables
// and the atlas import reads them on the way past.

/** Where imported sprites land, under core's upload directory. */
const ART_SUBDIR = 'atlas'

// ── configuration ──────────────────────────────────────────────────────────

/**
 * Is there a shard to ask?
 *
 * Both halves matter, exactly as in `shardClilocs.model`: a `baseUrl` on a
 * disabled config is an install that was set up and then switched off, and
 * calling it would spend a 12 s timeout to learn what the row already says.
 */
async function shardLinked() {
  try {
    const config = await uoLinkConfig.getSafe()
    return Boolean(config?.enabled && config?.baseUrl)
  } catch {
    return false
  }
}

function artDir() {
  return path.join(core.uploads.UPLOAD_DIR, ART_SUBDIR)
}

/**
 * The operator's own art map, which wins over anything imported.
 *
 * Read through the atlas model rather than re-implemented, so there is one
 * definition of where that file lives and what an absent one means.
 */
function operatorArt() {
  // eslint-disable-next-line global-require
  return require('../shardAtlas/shardAtlas.model').loadArtMap()
}

// ── writing a sprite ───────────────────────────────────────────────────────

/**
 * The filename one asset gets on disk.
 *
 * **Content-addressed on purpose.** A stable name per key (`uo-body-34.png`)
 * would be overwritten in place by an Update, and every browser and CDN that had
 * already cached it would keep serving last month's client's sprite — with
 * nothing anywhere to notice, because the database row would be correct. Putting
 * eight bytes of the hash in the name makes a changed sprite a changed URL.
 *
 * The old file is removed when a key's hash moves, so the directory tracks the
 * catalogue rather than accumulating one file per import forever.
 */
function fileNameFor(key, sha256) {
  const stem = key.replace(/[^a-zA-Z0-9]+/g, '-').replace(/^-+|-+$/g, '')
  return `uo-${stem}-${String(sha256).slice(0, 8)}.png`
}

/**
 * Write one sprite and return its filename, or null if it could not be written.
 *
 * Never throws. A full disk or a read-only volume must degrade to "this creature
 * has no picture" — which the whole site already renders correctly, because it is
 * the state every install was in until this phase — rather than failing an import
 * that has already fetched hundreds of others.
 */
function writeSprite(key, sha256, png) {
  const name = fileNameFor(key, sha256)

  try {
    fs.mkdirSync(artDir(), { recursive: true })
    fs.writeFileSync(path.join(artDir(), name), png)
    return name
  } catch (err) {
    log.warn('could not write an imported sprite', { key, error: err.message })
    return null
  }
}

/** Best-effort removal of a sprite a key no longer points at. */
function removeSprite(name) {
  if (!name) return

  try {
    fs.unlinkSync(path.join(artDir(), name))
  } catch {
    // Already gone, or never written. Either way there is nothing to do, and an
    // import must not fail because a file it was tidying up was tidied already.
  }
}

// ── the import ─────────────────────────────────────────────────────────────

/**
 * Import (or update) the body catalogue and the slug → body map.
 *
 * Returns a result rather than throwing, so a controller can render it and an
 * operator can read it:
 *
 *   `skipped`     no shard configured — the file era had no equivalent here
 *   `unavailable` the shard could not answer (down, plane off, no libgdiplus)
 *   `unchanged`   the client files match what was imported; nothing fetched
 *   `imported`    fetched and applied
 *   `needsReview` a key we hold has vanished from the shard's manifest
 *   `failed`      something went wrong mid-import
 *
 * `force` re-imports even when the client files are unchanged (which is also how
 * an operator recovers from a deleted uploads directory — the database still
 * holds the hashes, but the files behind them are gone). `approve` accepts a
 * catalogue that no longer offers keys we hold.
 */
async function importAssets({ force = false, approve = false } = {}) {
  if (!(await shardLinked())) {
    return {
      status: 'skipped',
      reason: 'uo-link is not configured, so there is no shard to read client files from',
    }
  }

  let sources

  try {
    sources = await bridge.sourceFingerprint()
  } catch (err) {
    return failure(err, 'client file manifest')
  }

  // §4.4: a Linux shard host without libgdiplus cannot render a sprite at all.
  // It is reported on the source gate precisely so an operator meets it while
  // setting the shard up rather than from an empty bestiary weeks later.
  if (sources.imaging && sources.imaging.ok === false) {
    return {
      status: 'unavailable',
      code: 'NO_IMAGING',
      reason: sources.imaging.reason || 'the shard host cannot render images',
    }
  }

  const meta = await db.getMeta().catch(() => null)

  if (!force && bridge.sameSources(sources, meta?.sources)) {
    const counts = await db.countAssets()
    const bodies = await db.countBodies()

    return {
      status: 'unchanged',
      assets: counts.total,
      stored: counts.stored,
      bodies: bodies.resolved,
      hashing: sources.hashing,
      importedAt: meta?.importedAt ?? null,
    }
  }

  let manifest

  try {
    manifest = await bridge.readManifest({ family: bridge.FAMILY })
  } catch (err) {
    return failure(err, 'asset manifest')
  }

  const held = await db.allAssets()
  const offered = new Set(manifest.rows.map((r) => r.key))

  // A key we hold that the shard no longer offers. An unmounted client volume and
  // a deliberate downgrade look identical from here, and the wrong guess deletes
  // artwork, so it is staged rather than applied — the same rule, and the same
  // reasoning, as a vanished cliloc overlay or a disappearing atlas facet.
  const vanished = [...held.keys()].filter((key) => !offered.has(key))

  if (vanished.length > 0 && !approve) {
    return {
      status: 'needsReview',
      reason:
        `${vanished.length} asset(s) this site holds are no longer offered by the shard; ` +
        'nothing was changed',
      vanished: vanished.slice(0, 50),
      vanishedCount: vanished.length,
    }
  }

  // The diff, and the whole reason stage 2 carries hashes and not pixels. An
  // unchanged key is skipped ONLY if its file is actually still on disk: the row
  // and the file can disagree (a wiped uploads volume, a restore from a database
  // dump), and re-fetching a sprite is far cheaper than a creature page with a
  // broken image on it.
  const wanted = manifest.rows.filter((row) => {
    const existing = held.get(row.key)
    if (!existing || existing.sha256 !== row.sha256) return true
    if (!existing.file) return true
    return !fs.existsSync(path.join(artDir(), existing.file))
  })

  let fetched = { assets: new Map(), missing: { absent: 0, unsupported: 0 } }

  if (wanted.length > 0) {
    try {
      fetched = await bridge.fetchAssets({
        keys: wanted.map((r) => r.key),
        catalog: manifest.catalog,
      })
    } catch (err) {
      return failure(err, 'asset content')
    }
  }

  const rows = []
  let written = 0

  for (const row of manifest.rows) {
    const existing = held.get(row.key)
    const got = fetched.assets.get(row.key)

    if (!got) {
      // Either it was unchanged and skipped, or the shard could not serve it. The
      // row is kept either way, with whatever file it already had — a key the
      // shard suddenly cannot render must not lose the picture we already hold.
      rows.push({ ...row, file: existing?.file ?? null })
      continue
    }

    const name = writeSprite(row.key, got.sha256, got.png)

    if (name) {
      written++
      if (existing?.file && existing.file !== name) removeSprite(existing.file)
    }

    rows.push({
      ...row,
      sha256: got.sha256 || row.sha256,
      bytes: got.bytes || row.bytes,
      width: got.width || row.width,
      height: got.height || row.height,
      body: got.body ?? row.body,
      direction: got.direction ?? row.direction,
      file: name ?? existing?.file ?? null,
    })
  }

  const removed = []

  if (vanished.length > 0) {
    for (const key of vanished) {
      removeSprite(held.get(key)?.file)
      removed.push(key)
    }
  }

  try {
    await db.saveAssets(rows, {
      catalog: manifest.catalog,
      extractorVersion: manifest.extractorVersion,
      family: bridge.FAMILY,
      playerBodies: manifest.playerBodies,
      sources: { files: sources.files, extractorVersion: sources.extractorVersion },
      count: rows.length,
    })
  } catch (err) {
    return { status: 'failed', reason: err.message }
  }

  const bodies = await resolveAtlasBodies()
  const art = await applyArt()

  log.info('asset import applied', {
    assets: rows.length,
    fetched: fetched.assets.size,
    written,
    absent: fetched.missing.absent,
    bodies: bodies.resolved,
    art: art.applied,
  })

  return {
    status: 'imported',
    catalog: manifest.catalog,
    extractorVersion: manifest.extractorVersion,
    assets: rows.length,
    fetched: fetched.assets.size,
    written,
    absent: fetched.missing.absent,
    unsupported: fetched.missing.unsupported,
    removed: removed.length,
    scanned: manifest.scanned,
    pages: manifest.pages,
    playerBodies: manifest.playerBodies,
    bodies,
    art,
  }
}

function failure(err, what) {
  if (err instanceof bridge.AssetBridgeError) {
    return { status: 'unavailable', code: err.code, reason: err.message }
  }

  log.warn(`asset import failed reading the ${what}`, { error: err.message })

  return { status: 'failed', reason: err.message }
}

// ── the body pass (§8) ─────────────────────────────────────────────────────

/**
 * Ask the shard for a body id for every creature the atlas knows.
 *
 * `shard_spawn_creatures.name` is the ServUO class name — the atlas build picks
 * the winning spelling of the spawn TYPE token rather than inventing a display
 * name — so this needs no new column to ask its question.
 *
 * Never throws: a shard that goes down between the asset fetch and this pass
 * leaves the assets imported and the map as it was, which is a strictly better
 * state than failing the whole import back to nothing.
 */
async function resolveAtlasBodies() {
  let creatures = []

  try {
    creatures = await atlasDb.allCreatureTypes()
  } catch (err) {
    return { resolved: 0, asked: 0, reason: err.message }
  }

  if (creatures.length === 0) {
    return { resolved: 0, asked: 0, reason: 'the spawn atlas has no creatures loaded' }
  }

  let rows

  try {
    rows = await bridge.resolveBodies({ creatures })
  } catch (err) {
    return { resolved: 0, asked: creatures.length, reason: err.message }
  }

  try {
    await db.replaceBodies(rows)
  } catch (err) {
    return { resolved: 0, asked: creatures.length, reason: err.message }
  }

  const tally = { ok: 0, unknown: 0, notCreature: 0, failed: 0 }

  for (const row of rows) {
    if (tally[row.status] === undefined) tally.failed++
    else tally[row.status]++
  }

  return { asked: creatures.length, answered: rows.length, resolved: tally.ok, tally }
}

// ── the derivation (§12) ───────────────────────────────────────────────────

/**
 * Point every atlas creature at its imported portrait.
 *
 * Two rules, and the second is the one worth stating:
 *
 *   1. The operator's `spawnAtlas.art.json` wins. Someone who drew their own
 *      creature portraits must not have them replaced by a sprite rip.
 *   2. A slug with neither is set back to NULL rather than left alone. A creature
 *      whose body stopped resolving — the operator removed a script package, say
 *      — would otherwise keep pointing at a file that is about to be deleted, and
 *      a broken image is worse than no image.
 */
async function applyArt() {
  const derived = await db.artBySlug()
  const operator = operatorArt()

  const map = { ...derived, ...operator }

  try {
    const applied = await atlasDb.setCreatureArt(map)
    return { applied, derived: Object.keys(derived).length, operator: Object.keys(operator).length }
  } catch (err) {
    log.warn('could not apply imported creature art', { error: err.message })
    return { applied: 0, derived: Object.keys(derived).length, error: err.message }
  }
}

// ── status ─────────────────────────────────────────────────────────────────

/**
 * What the admin panel renders: what is loaded, what the shard says, and whether
 * the two agree.
 *
 * Never throws and never fails a page: every branch that could — no shard, a
 * shard that is down, an asset plane the operator switched off — is a reported
 * state with a reason an operator can act on.
 */
async function getStatus() {
  const counts = await db.countAssets().catch(() => ({ total: 0, stored: 0 }))
  const bodies = await db.countBodies().catch(() => ({ total: 0, resolved: 0 }))
  const meta = await db.getMeta().catch(() => null)
  const families = await db.countByFamily().catch(() => ({}))

  const status = {
    loaded: {
      assets: counts.total,
      stored: counts.stored,
      creatures: bodies.total,
      resolved: bodies.resolved,
      catalog: meta?.catalog ?? null,
      extractorVersion: meta?.extractorVersion ?? null,
      importedAt: meta?.importedAt ?? null,
      // Item and land pictures, counted separately because they are a different
      // KIND of thing (§11, phase 5): no manifest, no set, and no "how many are
      // there" to compare against. `items` is how many the site has been asked
      // for and holds, which is the only number that means anything here.
      items: families.static?.stored ?? 0,
      land: families.land?.stored ?? 0,
    },
    shard: null,
    drift: null,
  }

  if (!(await shardLinked())) {
    status.reason = 'uo-link is not configured'
    return status
  }

  try {
    const sources = await bridge.sourceFingerprint()

    status.shard = {
      files: Object.keys(sources.files).length,
      extractorVersion: sources.extractorVersion,
      hashing: sources.hashing,
      complete: sources.complete,
      imaging: sources.imaging,
      // Which §5 families this overlay serves. A phase-3 or phase-4 overlay says
      // `['body']`, which is what an admin panel needs in order to say "update
      // your plugin" rather than showing an item-art pipeline that cannot work.
      families: sources.families,
    }

    status.drift = meta ? !bridge.sameSources(sources, meta.sources) : true
  } catch (err) {
    status.reason = err.message
    status.code = err instanceof bridge.AssetBridgeError ? err.code : 'UNAVAILABLE'
  }

  return status
}

module.exports = {
  ART_SUBDIR,
  artDir,
  fileNameFor,
  importAssets,
  resolveAtlasBodies,
  applyArt,
  getStatus,
}