local makepfs_sig = {
    0x4d, 0x61, 0x6b, 0x65, 0x50, 0x66, 0x73, 0x20,
    0x56, 0x65, 0x72, 0x73, 0x69, 0x6f, 0x6e, 0x31,
    0x2e, 0x32, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
}

function load_psp_index(cdutil)
    local pspval1_ent = cdutil:findpath "/PSP_GAME/USRDIR/PSPVAL1.PFS"
    if not pspval1_ent then error "VP-PSP iso seems wrong..." end
    local pspval1 = cdutil:cdfile(pspval1_ent)
    
    for k, v in ipairs(makepfs_sig) do
        if pspval1:readU8() ~= v then error "Wrong MakePfs signature." end
    end
    num_entries = pspval1:readU32()
    num_files = num_entries
    
    local idx_pos = pspval1:readU32()
    local index = {}
    
    pspval1:seek(2048 * idx_pos + 4)
    local last_sector = 1
    for i = 1, num_entries - 1 do
        local sector = pspval1:readU32()
        local abssector = pspval1_ent.Sector + sector
        index[i] = { sector = abssector, cd = cdutil }
        if i ~= 1 then
            index[i - 1].size = sector - last_sector
        end
        last_sector = sector
    end
    index[num_entries - 1].size = idx_pos - last_sector
    
    for i = 1, num_entries - 1 do
        if index[i].size == 0 then index[i] = nil else log("Entry " .. i .. ", sector " .. index[i].sector .. ", nsectors = " .. index[i].size) end
    end
    
    return index
end

function load_index(cdutil)
    if got_psp then return load_psp_index(cdutil) end
    local vp_sec, cfat, csiz, fat, siz, fkey, skey, fkey_pos, skey_pos
    
    vp_sec = 150
    cfat = cdutil:cdfile(vp_sec, num_entries * 4)
    csiz = cdutil:cdfile(vp_sec + num_entries * 4 / 2048, num_entries)
    fat = Buffer(true)
    siz = Buffer(true)
    fkey = Buffer(true)
    skey = Buffer(true)
    cfat:seek(num_entries * 4 - fkey_size)
    csiz:seek(num_entries - skey_size)
    fkey:copyfrom(cfat, fkey_size)
    skey:copyfrom(csiz, skey_size)
    cfat:seek(0)
    csiz:seek(0)
    
    fkey_pos = 0
    skey_pos = 0
    
    print "Decrypting index..."
    for i = 0, (num_entries * 4 - 1) do
        fat:writeU8(xorB(cfat:readU8(), fkey:readU8()))
        fkey_pos = fkey_pos + 1
        if fkey_pos == fkey_size then
            fkey_pos = 0
            fkey:seek(0)
        end
    end
    
    for i = 0, (num_entries - 1) do
        siz:writeU8(xorB(csiz:readU8(), skey:readU8()))
        skey_pos = skey_pos + 1
        if skey_pos == skey_size then
            skey_pos = 0
            skey:seek(0)
        end
    end
    
    cfat:destroy()
    csiz:destroy()
    fkey:seek(0)
    skey:seek(0)
    
    print "Done."
    
    local o, m, s, f, size_high, size
    
    local fr = fat:readU32()
    local sr = siz:readU8()
    local index = {}
    for i = 1, (num_entries - 1) do
        m = fat:readU8()
        s = fat:readU8()
        f = fat:readU8()
        size_high = fat:readU8()
        sector = from_MSF(m, s, f)
        size = siz:readU8() + size_high * 256
        if (sector ~= 4294967146) then
            log("Entry " .. i .. ", sector " .. sector .. ", nsectors = " .. size)
            index[i] = { sector = sector, size = size, cd = cdutil }
        end
    end
    fat:destroy()
    siz:destroy()
    
    return index, fkey, skey, fr, sr
end

function add_file(cindex, iso, file, i)
    local size_full = math.ceil(file:getsize() / 2048)
    local dest_sector = iso:putfile(file)
    local _, m, s, f = to_MSF(dest_sector)
    local size_high = math.floor(size_full / 256)
    local size = size_full - size_high * 256
    log("Putting file " .. i .. " at " .. dest_sector .. " - size = " .. size_full)
    cindex.fat:wseek(i * 4)
    cindex.siz:wseek(i)
    cindex.fat:writeU8(m)
    cindex.fat:writeU8(s)
    cindex.fat:writeU8(f)
    cindex.fat:writeU8(size_high)
    cindex.siz:writeU8(size)
end

function close_index(cindex, iso)
    for i = cindex.fat:getsize(), (num_entries * 4 - 1) do
        cindex.fat:writeU8(0)
    end
    
    for i = cindex.siz:getsize(), (num_entries - 1) do
        cindex.siz:writeU8(0)
    end

    local fkey_pos = 0
    local skey_pos = 0
    local cfat = Buffer(true)
    local csiz = Buffer(true)
    cindex.fat:seek(0)
    cindex.siz:seek(0)
    cindex.fkey:seek(0)
    cindex.skey:seek(0)

    for i = 0, (num_entries * 4 - 1) do
        cfat:writeU8(xorB(cindex.fat:readU8(), cindex.fkey:readU8()))
        fkey_pos = fkey_pos + 1
        if fkey_pos == fkey_size then
            fkey_pos = 0
            cindex.fkey:seek(0)
        end
    end

    for i = 0, (num_entries - 1) do
        csiz:writeU8(xorB(cindex.siz:readU8(), cindex.skey:readU8()))
        skey_pos = skey_pos + 1
        if skey_pos == skey_size then
            skey_pos = 0
            cindex.skey:seek(0)
        end
    end

    iso:putfile(cfat, -1, 150)
    iso:putfile(csiz, -1, 160)

    cfat:destroy()
    csiz:destroy()
end

function psp_add_file(cindex, iso, file, i)
    local size_full = math.ceil(file:getsize() / 2048)
    local dest_sector = iso:putfile(file)
    cindex.index[i] = { size = size_fill, sector = dest_sector }
    log("Putting file " .. i .. " at " .. dest_sector .. " - size = " .. size_full)
end

function copyfile(path, name, dirtree, iso, cdutil)
    local dirent = cdutil:findpath(path .. "/" .. name)
    if not dirent then error("Failing finding path " .. path .. "/" .. name) end
    iso:createfile(dirtree, name, cdutil:cdfile(dirent), dirent):setbasicsxa()
end

function psp_close_index(cindex, iso, cdutil)
    local index_sec = iso:getdispsect()
    local indexfile = Buffer(true)
    local indexhead = Buffer(true)
    indexhead:write "MakePfs Version1.20"
    indexhead:writeU8(0)
    indexhead:writeU32(0)
    indexhead:writeU32(0)
    indexhead:writeU32(0)
    indexhead:writeU32(num_files)
    indexhead:writeU32(index_sec - pspval1_sec)
    indexhead:writeU32(0)
    for i = indexhead:getsize(), 2047 do
        indexhead:writeU8(0x98)
    end
    iso:putfile(indexhead, -1, pspval1_sec)
    indexfile:writeU32(1)
    local last_entry = nil
    for i = 1, num_files - 1 do
        if cindex.index[i] then
            last_entry = cindex.index[i].sector - pspval1_sec
            indexfile:writeU32(last_entry)
        else
            indexfile:writeU32(last_entry)
        end
    end
    local more_bytes = alignment(indexfile:getsize(), 2048)
    for i = 1, more_bytes do
        indexfile:writeU8(0x98)
    end
    iso:putfile(indexfile)
    psp_dirtrees.PSPVAL1.size = (iso:getdispsect() - pspval1_sec) * 2048
    
    indexfile:destroy()
    indexhead:destroy()

    local cp = function(path, name, dirtree) copyfile(path, name, dirtree, iso, cdutil) end
    for _, f in ipairs { "Field_master.prx", "Camp_master.prx", "MiniMap_master.prx", "WldMap_master.prx", "GodCamp_master.prx", "moviepac.dat" } do
        cp("/PSP_GAME/USRDIR", f, psp_dirtrees.USRDIR)
    end
end

function prepare_index(iso, fkey, skey, fr, sr)
    if got_psp then
        return { add_file = psp_add_file, close_index = psp_close_index, index = { } }
    end
    
    local false_sect = {}
    for i = 1, 13 do
        iso:createsector(false_sect, MODE2_FORM1)
    end
    local ret = { fat = Buffer(true), siz = Buffer(true), fkey = fkey, skey = skey, add_file = add_file, close_index = close_index }
    ret.fat:writeU32(fr)
    ret.siz:writeU8(sr)
    
    return ret
end