-- Launcher save Import/Export glue (src/import/SaveFileIO.lua): the end-to-end
-- importToSlot -> listSlots roundtrip and the exportActiveSlot output-byte
-- sanity check, driven love-free through the same in-memory filesystem stub
-- tests/engine/save_slots.lua uses.  A synthetic 32KB SRAM image is built via
-- GenSave.encode (no real save checked in); a fixture-gated case exercises the
-- real .sav when POKEPORT_SAV_FIXTURE points at one.
--   luajit tests/engine/save_file_io_tests.lua

package.path = "./?.lua;./?/init.lua;" .. package.path

local T = require("tests.harness")
local check, eq = T.check, T.eq
love = love or require("tests.love_stub")

local GenSave = require("src.save_convert.GenSave")
local SaveConvert = require("src.save_convert.SaveConvert")
local SaveData = require("src.core.SaveData")
local GameVersion = require("src.core.GameVersion")
local SaveFileIO = require("src.import.SaveFileIO")

local realFS = love.filesystem

-- A love.filesystem stub keyed by full path, extended past save_slots' memfs
-- with the export surface SaveFileIO reaches for (createDirectory /
-- getSaveDirectory).  A directory key is implied by any file under it.
local function memfs(files)
  return {
    files = files,
    write = function(path, content) files[path] = content return true end,
    read = function(path) return files[path] end,
    remove = function(path) files[path] = nil return true end,
    getInfo = function(path)
      if files[path] then return { type = "file" } end
      local prefix = path .. "/"
      for key in pairs(files) do
        if key:sub(1, #prefix) == prefix then return { type = "directory" } end
      end
      return nil
    end,
    createDirectory = function() return true end,
    getSaveDirectory = function() return "/fake/save" end,
  }
end

local function fresh()
  local files = {}
  love.filesystem = memfs(files)
  SaveData.resetSlotState()
  GameVersion.set("red")
  return files
end

-- ---- crosswalk data + synthetic 32KB save (built the way the codec tests do)
-- Gen1 encode/decode needs Red species/item indices from data/generated/,
-- which CI never has.  Skip cleanly so the ROM-free T1/T2 tier stays green.
local loadPokemon = loadfile("data/generated/pokemon.lua")
if not loadPokemon then
  print("save_file_io skipped (needs data/generated/ for Gen1 save codec)")
  os.exit(0)
end

GenSave.setCharmap(loadfile("src/save_convert/data/charmap.lua")())
local data = {
  pokemon = loadPokemon(),
  moves = loadfile("data/generated/moves.lua")(),
  items = loadfile("data/generated/items.lua")(),
  maps = loadfile("data/generated/maps.lua")(),
  eventFlags = loadfile("src/save_convert/data/event_flags.lua")(),
}

-- independent checksum re-derivation (complement of the additive byte sum) so
-- the export sanity check does not trust the encoder that wrote it
local bit = require("bit")
local OFF = GenSave.OFFSETS
local function rawChecksum(bytes, from, to)
  local sum = 0
  for i = from, to - 1 do sum = bit.band(sum + bytes:byte(i + 1), 0xFF) end
  return bit.band(bit.bnot(sum), 0xFF)
end
local function mainChecksumValid(bytes)
  return rawChecksum(bytes, OFF.checksumStart, OFF.checksumEnd)
    == bytes:byte(OFF.mainChecksum + 1)
end

local function syntheticSave(name)
  local seed = SaveData.newGame({ playerName = name, rivalName = "BLUE" })
  seed.money = 4321
  seed.inventory = { POTION = 2, POKE_BALL = 7, BOULDERBADGE = 1 }
  seed.bagOrder = { "POTION", "POKE_BALL" }
  seed.party = { {
    species = "SQUIRTLE", level = 6, exp = 200,
    dvs = { hp = 1, attack = 2, defense = 3, speed = 4, special = 5 },
    statExp = { hp = 0, attack = 0, defense = 0, speed = 0, special = 0 },
    stats = { hp = 22, attack = 12, defense = 13, speed = 11, special = 12 },
    hp = 22, status = nil,
    moves = { { id = "TACKLE", pp = 35, ppUps = 0 } },
    nickname = "SQ", ot = name, otId = seed.player.id, catchRate = 45,
  } }
  -- The current-map view pointer is part of wMainData's map cache, not a
  -- modeled save field.  Pokémon Red restores that cache before Continue,
  -- so it is a useful canary for the import -> slot -> export path.
  local raw = GenSave.encode(seed, data, nil)
  local cacheOff = OFF.mainData + 104
  local cacheTemplate = raw:sub(1, cacheOff) .. string.char(0xA5)
    .. raw:sub(cacheOff + 2)
  return GenSave.encode(seed, data, cacheTemplate)
end

-- ---------------------------------------------- importToSlot -> listSlots

do
  fresh()
  local bytes = syntheticSave("IMP")
  eq(#bytes, GenSave.SAVE_SIZE, "the synthetic save is 32768 bytes")

  local ok, slotId = SaveFileIO.importToSlot(bytes, "red")
  eq(ok, true, "importToSlot succeeds on a valid 32KB save")
  eq(slotId, "slot1", "the first import registers slot1")

  local slots = SaveData.listSlots("red")
  eq(#slots, 1, "the imported save shows up as exactly one slot")
  eq(slots[1].id, "slot1", "the listed slot is slot1")
  eq(slots[1].exists, true, "the imported slot reports a save present")
  eq(slots[1].name, "IMP", "the imported slot surfaces the decoded player name")
  eq(SaveData.activeSlot("red"), "slot1", "the imported slot is made active")

  -- the slot loads cleanly (meta re-stamped from gen1_import to the numeric
  -- format, so runMigrations does not choke)
  local loaded = SaveData.load("red")
  check(loaded ~= nil, "the imported slot loads back")
  eq(loaded and loaded.player.name, "IMP", "loaded save keeps the player name")
  eq(loaded and loaded.money, 4321, "loaded save keeps the money")
  eq(loaded and #loaded.party, 1, "loaded save keeps the party")

  -- a second import allocates a fresh slot and makes it active
  local ok2, slot2 = SaveFileIO.importToSlot(syntheticSave("TWO"), "red")
  eq(ok2, true, "a second import succeeds")
  eq(slot2, "slot2", "the second import allocates slot2")
  eq(#SaveData.listSlots("red"), 2, "both imported slots are listed")
  eq(SaveData.activeSlot("red"), "slot2", "the newest import becomes active")
end

-- ---------------------------------------------- exportActiveSlot byte sanity

do
  local files = fresh()
  SaveFileIO.importToSlot(syntheticSave("EXP"), "red")

  local ok, path = SaveFileIO.exportActiveSlot("red")
  eq(ok, true, "exportActiveSlot succeeds for an active slot with a save")
  eq(path, "/fake/save/exports/red/gen1recomp-red-slot1.sav",
    "the export path is absolute under exports/<version>/")

  local outBytes = files["exports/red/gen1recomp-red-slot1.sav"]
  check(outBytes ~= nil, "the export file lands in the per-game exports/ folder")
  eq(outBytes and #outBytes, GenSave.SAVE_SIZE, "the export is exactly 32768 bytes")
  check(outBytes and mainChecksumValid(outBytes),
    "the export carries a valid main-data checksum")
  eq(outBytes and outBytes:byte(OFF.mainData + 105), 0xA5,
    "the export keeps the saved current-map cache")

  -- the export re-imports to an equivalent save
  local re = SaveConvert.importSav(outBytes, "red")
  check(re ~= nil, "the export re-imports through SaveConvert")
  eq(re and re.player and re.player.name, "EXP", "the export round-trips the player name")
  eq(re and re.party[1] and re.party[1].species, "SQUIRTLE",
    "the export round-trips the party")
  eq(re and re.inventory and re.inventory.BOULDERBADGE, 1,
    "the export round-trips a badge")
end

-- ---------------------------------------------- failure UX (never raises)

do
  fresh()
  -- wrong size via a DroppedFile-shaped source (100 bytes)
  local shortFile = {
    _bytes = string.rep("\0", 100),
    open = function() return true end,
    getSize = function(self) return #self._bytes end,
    read = function(self) return self._bytes end,
    close = function() return true end,
  }
  local ok, err = SaveFileIO.importToSlot(shortFile, "red")
  eq(ok, false, "a wrong-size save is rejected, not imported")
  check(type(err) == "string" and err:find("32", 1, true) ~= nil,
    "the wrong-size error names the required size")
  eq(#SaveData.listSlots("red"), 0, "a rejected import creates no slot")

  -- bad checksum: flip a modeled byte in an otherwise valid image
  local good = syntheticSave("BAD")
  local corrupt = good:sub(1, OFF.money)
    .. string.char((good:byte(OFF.money + 1) + 1) % 256)
    .. good:sub(OFF.money + 2)
  local okc, errc = SaveFileIO.importToSlot(corrupt, "red")
  eq(okc, false, "a bad-checksum save is rejected")
  check(type(errc) == "string" and errc:find("checksum", 1, true) ~= nil,
    "the bad-checksum error mentions the checksum")
  eq(#SaveData.listSlots("red"), 0, "a rejected checksum creates no slot")

  -- export with nothing to export
  local oke, erre = SaveFileIO.exportActiveSlot("red")
  eq(oke, false, "exportActiveSlot fails cleanly when there is no save")
  check(type(erre) == "string", "the empty-export failure carries a message")
end

-- ---------------------------------------------- oversize / truncated policy
-- A .sav LARGER than 32768 bytes whose first 32768 bytes carry a valid
-- main-data checksum is a cartridge save with a trailing emulator RTC footer
-- (VBA appends 44/48 bytes -- bgb.bircd.org/rtcsave.html).  Without force the
-- import must NOT happen silently: it returns (false, nil, {needsConfirm})
-- so the launcher can ask.  With force the surplus is dropped.  A file
-- SHORTER than 32768 is refused unless its checksum region is intact, in
-- which case it imports zero-padded (a truncated box region, not a loss).

-- DroppedFile-shaped source for arbitrary bytes (readSource disambiguates a
-- raw string of length != 32768 as a path, so tests hand a file object).
local function fileSource(bytes)
  return {
    _bytes = bytes,
    open = function() return true end,
    getSize = function(self) return #self._bytes end,
    read = function(self) return self._bytes end,
    close = function() return true end,
  }
end

-- A realistic 44-byte VBA MBC3 RTC footer (4 dwords, 16-byte latched copies,
-- 8-byte unix timestamp, 4-byte unix timestamp -- bgb.bircd.org/rtcsave.html).
local function rtcFooter()
  local parts = {}
  local function pushLe(v)
    parts[#parts + 1] = string.char(v % 256, math.floor(v / 256) % 256,
      math.floor(v / 65536) % 256, math.floor(v / 16777216) % 256)
  end
  pushLe(27)            -- days
  pushLe(29)            -- hours
  pushLe(11)            -- minutes
  pushLe(200)           -- seconds
  parts[#parts + 1] = string.rep("\0", 16)  -- latched RTC copies
  parts[#parts + 1] = string.rep("\0", 8)   -- 64-bit unix timestamp
  pushLe(0x669A00BF)    -- 32-bit unix timestamp (2024-07-09)
  return table.concat(parts)
end

do
  local oversize = syntheticSave("OVS") .. rtcFooter()
  eq(#oversize, 32768 + 44, "the oversize fixture is 32812 bytes like the real VBA save")

  local files = fresh()
  local ok, res, info = SaveFileIO.importToSlot(fileSource(oversize), "red")
  eq(ok, false, "an oversize valid save is not imported without confirmation")
  eq(res, nil, "the oversize result carries no error string")
  check(info ~= nil and info.needsConfirm == true, "the oversize result requests confirmation")
  eq(info and info.size, #oversize, "the confirmation carries the actual file size")
  eq(#SaveData.listSlots("red"), 0, "no slot is created before confirmation")

  -- forcing the import truncates the footer away
  local fok, slotId = SaveFileIO.importToSlot(fileSource(oversize), "red", true)
  eq(fok, true, "force imports the truncated save")
  local loaded = SaveData.load("red")
  eq(loaded and loaded.player.name, "OVS", "the forced import keeps the player name")
  eq(SaveData.activeSlot("red"), slotId, "the forced import becomes active")

  local eok, path = SaveFileIO.exportActiveSlot("red")
  eq(eok, true, "the forced import exports")
  local rel = path:gsub("^/fake/save/", "")
  local outBytes = files[rel]
  eq(outBytes and #outBytes, GenSave.SAVE_SIZE,
    "the export of a forced import is exactly 32768 bytes (footer dropped)")
  check(outBytes and mainChecksumValid(outBytes),
    "the forced-import export carries a valid main-data checksum")
end

do
  -- oversize but corrupt: flip a byte inside the checksummed region
  local bad = syntheticSave("BAD") .. rtcFooter()
  bad = bad:sub(1, OFF.money)
    .. string.char((bad:byte(OFF.money + 1) + 1) % 256)
    .. bad:sub(OFF.money + 2)
  fresh()
  local ok, res = SaveFileIO.importToSlot(fileSource(bad), "red")
  eq(ok, false, "an oversize file with a bad checksum is rejected")
  check(type(res) == "string" and res:find("checksum", 1, true) ~= nil,
    "the oversize bad-checksum error mentions the checksum")
  eq(#SaveData.listSlots("red"), 0, "no slot is created for a bad oversize file")
end

do
  -- truncated to 14000 bytes: >= 13572 keeps the whole checksum region and the
  -- stored checksum byte intact, so the checksum validates and the save imports
  -- with the missing tail (box banks) zero-filled.
  local truncated = syntheticSave("SHORT"):sub(1, 14000)
  check(truncated:len() >= OFF.mainChecksum + 1,
    "the truncated fixture still carries the stored checksum byte")
  fresh()
  local ok, slotId = SaveFileIO.importToSlot(fileSource(truncated), "red")
  eq(ok, true, "a truncated file with a valid checksum imports zero-padded")
  local loaded = SaveData.load("red")
  eq(loaded and loaded.player.name, "SHORT", "the truncated import keeps the player name")
  eq(#SaveData.listSlots("red"), 1, "the truncated import creates a slot")
  eq(SaveData.activeSlot("red"), slotId, "the truncated import becomes active")

  -- truncated but too short to even carry the checksum byte -> refused
  local short = truncated:sub(1, OFF.mainChecksum)
  local sok, serr = SaveFileIO.importToSlot(fileSource(short), "red")
  eq(sok, false, "a file too short to hold a checksum byte is refused")
  check(type(serr) == "string" and serr:find("32", 1, true) ~= nil,
    "the too-short error names the required size")
  eq(#SaveData.listSlots("red"), 1, "the too-short refusal creates no new slot")
end

-- ---------------------------------------------- fixture-gated real save

do
  local fixturePath = os.getenv("POKEPORT_SAV_FIXTURE")
  local fixtureBytes
  if fixturePath then
    local ff = io.open(fixturePath, "rb")
    if ff then
      fixtureBytes = ff:read("*a")
      ff:close()
      if #fixtureBytes ~= GenSave.SAVE_SIZE then fixtureBytes = nil end
    end
  end
  if not fixtureBytes then
    print("save_file_io fixture case skipped (set POKEPORT_SAV_FIXTURE to a 32KB .sav)")
  else
    local files = fresh()
    local ok, slotId = SaveFileIO.importToSlot(fixtureBytes, "red")
    eq(ok, true, "fixture: a real .sav imports to a slot")
    check(slotId ~= nil, "fixture: the import returns a slot id")

    local slots = SaveData.listSlots("red")
    eq(#slots, 1, "fixture: the real save shows as one slot")
    check(slots[1].exists and type(slots[1].name) == "string" and #slots[1].name > 0,
      "fixture: the imported slot has a non-empty player name")

    local loaded = SaveData.load("red")
    check(loaded ~= nil and #loaded.party >= 1 and #loaded.party <= 6,
      "fixture: the imported slot loads with a 1..6 party")

    local eok, path = SaveFileIO.exportActiveSlot("red")
    eq(eok, true, "fixture: the imported real save exports")
    local rel = path:gsub("^/fake/save/", "")
    local outBytes = files[rel]
    eq(outBytes and #outBytes, GenSave.SAVE_SIZE, "fixture: the export is 32768 bytes")
    check(outBytes and mainChecksumValid(outBytes),
      "fixture: the export has a valid main-data checksum")
  end
end

-- ---------------------------------------------- #206: exported map + position
-- Regression guard for issue #206 ("exported .sav loads as a glitch map /
-- crashes in an emulator"). The Gen1 continue path rebuilds the entire
-- overworld from the saved current-map byte and the player's tile coords
-- (engine/menus/main_menu.asm SpecialEnterMap -> ResetPlayerSpriteData ->
-- EnterMap -> LoadMapHeader), so the two ways a real cartridge glitches on
-- Continue are (a) wCurMap not resolving to a real map header, and (b) the
-- player's wYCoord/wXCoord falling outside the map's walk grid. A cell is 2x2
-- background tiles (home/overworld.asm), so a WxH-block map is 2W x 2H cells
-- and valid coords are 0..2W-1 / 0..2H-1. Drive the launcher's real export
-- path (import -> SaveData.load -> exportActiveSlot) and assert the emitted
-- bytes land a loadable player across interior/outdoor/cave maps, including
-- each map's far corner, so this class of corruption cannot slip back in.
do
  local mapsByIndex = {}
  for id, def in pairs(data.maps) do
    if def.index then mapsByIndex[def.index] = id end
  end

  -- One export cycle through the exact glue the SAVE FILES card uses. Returns
  -- the raw exported image, or nil if any stage refused (checked by callers).
  local function exportedThrough(mapId, x, y)
    local files = fresh()
    local seed = SaveData.newGame({ playerName = "JOHN", rivalName = "BLUE" })
    seed.player.map, seed.player.x, seed.player.y = mapId, x, y
    -- a plausible mid-game party so the slot is not a blank new game
    seed.party = { {
      species = "SQUIRTLE", level = 16, exp = 4000,
      dvs = { hp = 1, attack = 2, defense = 3, speed = 4, special = 5 },
      statExp = { hp = 0, attack = 0, defense = 0, speed = 0, special = 0 },
      stats = { hp = 44, attack = 28, defense = 31, speed = 26, special = 30 },
      hp = 44, moves = { { id = "TACKLE", pp = 35, ppUps = 0 } },
      nickname = "SQ", ot = "JOHN", otId = seed.player.id, catchRate = 45,
    } }
    if not SaveFileIO.importToSlot(GenSave.encode(seed, data, nil), "red") then return nil end
    if not SaveData.load("red") then return nil end
    if not SaveFileIO.exportActiveSlot("red") then return nil end
    return files["exports/red/gen1recomp-red-slot1.sav"]
  end

  local function assertLoadable(label, mapId, x, y)
    local def = data.maps[mapId]
    if not def then return end -- this data set lacks the map; skip silently
    local out = exportedThrough(mapId, x, y)
    check(out ~= nil and #out == GenSave.SAVE_SIZE,
      label .. ": exports a 32768-byte image through the launcher path")
    if not out then return end
    -- (a) wCurMap resolves: an unresolved index loads a garbage header, the
    -- #206 glitch/crash itself
    eq(mapsByIndex[out:byte(OFF.curMap + 1)], mapId,
      label .. ": exported wCurMap resolves to the saved map")
    -- (b) tile coords inside the 2W x 2H cell grid, and unchanged by the round trip
    local cx, cy = out:byte(OFF.xCoord + 1), out:byte(OFF.yCoord + 1)
    check(cx <= 2 * def.width - 1 and cy <= 2 * def.height - 1,
      ("%s: player cell (%d,%d) is in-bounds for the %dx%d-block map")
        :format(label, cx, cy, def.width, def.height))
    eq(cx, x, label .. ": wXCoord survives load -> export unchanged")
    eq(cy, y, label .. ": wYCoord survives load -> export unchanged")
    check(mainChecksumValid(out), label .. ": exported main-data checksum is valid")
  end

  assertLoadable("bedroom interior", "REDS_HOUSE_2F", 3, 6)
  assertLoadable("outdoor town", "PALLET_TOWN", 5, 6)
  assertLoadable("outdoor city", "CERULEAN_CITY", 27, 15)
  assertLoadable("cave floor", "MT_MOON_1F", 5, 5)
  -- the map's far corner (2W-1, 2H-1): proves the boundary coord writes and
  -- survives without truncation or an off-by-one out-of-bounds
  if data.maps.VIRIDIAN_CITY then
    local d = data.maps.VIRIDIAN_CITY
    assertLoadable("far corner", "VIRIDIAN_CITY", 2 * d.width - 1, 2 * d.height - 1)
  end
end

love.filesystem = realFS

T.finish("save_file_io")