local helpers = require("test.unit.helpers")(after_each)
local itp = helpers.gen_itp(it)

local ffi     = helpers.ffi
local eq      = helpers.eq

local lib = helpers.cimport('./src/nvim/mbyte.h', './src/nvim/charset.h', './src/nvim/grid.h')

describe('mbyte', function()
  -- Convert from bytes to string
  local function to_string(bytes)
    local s = {}
    for i = 1, #bytes do
      s[i] = string.char(bytes[i])
    end
    return table.concat(s)
  end

  before_each(function()
  end)

  itp('utf_ptr2char', function()
    -- For strings with length 1 the first byte is returned.
    for c = 0, 255 do
      eq(c, lib.utf_ptr2char(to_string({c, 0})))
    end

    -- Some ill formed byte sequences that should not be recognized as UTF-8
    -- First byte: 0xc0 or 0xc1
    -- Second byte: 0x80 .. 0xbf
    --eq(0x00c0, lib.utf_ptr2char(to_string({0xc0, 0x80})))
    --eq(0x00c1, lib.utf_ptr2char(to_string({0xc1, 0xbf})))
    --
    -- Sequences with more than four bytes
  end)

  for n = 0, 0xF do
    itp(('utf_char2bytes for chars 0x%x - 0x%x'):format(n * 0x1000, n * 0x1000 + 0xFFF), function()
      local char_p = ffi.typeof('char[?]')
      for c = n * 0x1000, n * 0x1000 + 0xFFF do
        local p = char_p(4, 0)
        lib.utf_char2bytes(c, p)
        eq(c, lib.utf_ptr2char(p))
        eq(lib.vim_iswordc(c), lib.vim_iswordp(p))
      end
    end)
  end

  describe('utfc_ptr2schar_len', function()
    local function test_seq(seq)
      local firstc = ffi.new("int[1]")
      local buf = ffi.new("char[32]")
      lib.schar_get(buf, lib.utfc_ptr2schar_len(to_string(seq), #seq, firstc))
      return {ffi.string(buf), firstc[0]}
    end

    local function byte(val)
      return {string.char(val), val}
    end

    itp('1-byte sequences', function()
      eq({'', 0}, test_seq{0})
      for c = 1, 127 do
        eq(byte(c), test_seq{c})
      end
      for c = 128, 255 do
        eq({'', c}, test_seq{c})
      end
    end)

    itp('2-byte sequences', function()
      -- No combining characters
      eq(byte(0x7f), test_seq{0x7f, 0x7f})
      -- No combining characters
      eq(byte(0x7f), test_seq{0x7f, 0x80})

      -- No UTF-8 sequence
      eq({'', 0xc2}, test_seq{0xc2, 0x7f})
      -- One UTF-8 character
      eq({'\xc2\x80', 0x80}, test_seq{0xc2, 0x80})
      -- No UTF-8 sequence
      eq({'', 0xc2}, test_seq{0xc2, 0xc0})
    end)

    itp('3-byte sequences', function()
      -- No second UTF-8 character
      eq(byte(0x7f), test_seq{0x7f, 0x80, 0x80})
      -- No combining character
      eq(byte(0x7f), test_seq{0x7f, 0xc2, 0x80})

      -- Combining character is U+0300
      eq({"\x7f\xcc\x80", 0x7f}, test_seq{0x7f, 0xcc, 0x80})

      -- No UTF-8 sequence
      eq({'', 0xc2}, test_seq{0xc2, 0x7f, 0xcc})
      -- Incomplete combining character
      eq({"\xc2\x80", 0x80}, test_seq{0xc2, 0x80, 0xcc})

      -- One UTF-8 character (composing only)
      eq({" \xe2\x83\x90", 0x20d0}, test_seq{0xe2, 0x83, 0x90})
    end)

    itp('4-byte sequences', function()

      -- No following combining character
      eq(byte(0x7f), test_seq{0x7f, 0x7f, 0xcc, 0x80})
      -- No second UTF-8 character
      eq(byte(0x7f), test_seq{0x7f, 0xc2, 0xcc, 0x80})

      -- Combining character U+0300
      eq({"\x7f\xcc\x80", 0x7f}, test_seq{0x7f, 0xcc, 0x80, 0xcc})

      -- No UTF-8 sequence
      eq({'', 0xc2}, test_seq{0xc2, 0x7f, 0xcc, 0x80})
      -- No following UTF-8 character
      eq({"\xc2\x80", 0x80}, test_seq{0xc2, 0x80, 0xcc, 0xcc})
      -- Combining character U+0301
      eq({"\xc2\x80\xcc\x81", 0x80}, test_seq{0xc2, 0x80, 0xcc, 0x81})

      -- One UTF-8 character
      eq({"\xf4\x80\x80\x80", 0x100000}, test_seq{0xf4, 0x80, 0x80, 0x80})
    end)

    itp('5+-byte sequences', function()
      -- No following combining character
      eq(byte(0x7f), test_seq{0x7f, 0x7f, 0xcc, 0x80, 0x80})
      -- No second UTF-8 character
      eq(byte(0x7f), test_seq{0x7f, 0xc2, 0xcc, 0x80, 0x80})

      -- Combining character U+0300
      eq({"\x7f\xcc\x80", 0x7f}, test_seq{0x7f, 0xcc, 0x80, 0xcc, 0x00})

      -- Combining characters U+0300 and U+0301
      eq({"\x7f\xcc\x80\xcc\x81", 0x7f}, test_seq{0x7f, 0xcc, 0x80, 0xcc, 0x81})
      -- Combining characters U+0300, U+0301, U+0302
      eq({"\x7f\xcc\x80\xcc\x81\xcc\x82", 0x7f}, test_seq{0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82})
      -- Combining characters U+0300, U+0301, U+0302, U+0303
      eq({"\x7f\xcc\x80\xcc\x81\xcc\x82\xcc\x83", 0x7f}, test_seq{0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xcc, 0x83})
      -- Combining characters U+0300, U+0301, U+0302, U+0303, U+0304
      eq({"\x7f\xcc\x80\xcc\x81\xcc\x82\xcc\x83\xcc\x84", 0x7f}, test_seq{0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xcc, 0x83, 0xcc, 0x84})
      -- Combining characters U+0300, U+0301, U+0302, U+0303, U+0304, U+0305
      eq({"\x7f\xcc\x80\xcc\x81\xcc\x82\xcc\x83\xcc\x84\xcc\x85", 0x7f}, test_seq{0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xcc, 0x83, 0xcc, 0x84, 0xcc, 0x85})

      -- Combining characters U+0300, U+0301, U+0302, U+0303, U+0304, U+0305, U+0306
      eq({"\x7f\xcc\x80\xcc\x81\xcc\x82\xcc\x83\xcc\x84\xcc\x85\xcc\x86", 0x7f}, test_seq{0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xcc, 0x83, 0xcc, 0x84, 0xcc, 0x85, 0xcc, 0x86})

      -- Only three following combining characters U+0300, U+0301, U+0302
      eq({"\x7f\xcc\x80\xcc\x81\xcc\x82", 0x7f}, test_seq{0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xc2, 0x80, 0xcc, 0x84, 0xcc, 0x85})

      -- No UTF-8 sequence
      eq({'', 0xc2}, test_seq{0xc2, 0x7f, 0xcc, 0x80, 0x80})
      -- No following UTF-8 character
      eq({"\xc2\x80", 0x80}, test_seq{0xc2, 0x80, 0xcc, 0xcc, 0x80})
      -- Combining character U+0301
      eq({"\xc2\x80\xcc\x81", 0x80}, test_seq{0xc2, 0x80, 0xcc, 0x81, 0x7f})
      -- Combining character U+0301
      eq({"\xc2\x80\xcc\x81", 0x80}, test_seq{0xc2, 0x80, 0xcc, 0x81, 0xcc})

      -- One UTF-8 character
      eq({"\xf4\x80\x80\x80", 0x100000}, test_seq{0xf4, 0x80, 0x80, 0x80, 0x7f})

      -- One UTF-8 character
      eq({"\xf4\x80\x80\x80", 0x100000}, test_seq{0xf4, 0x80, 0x80, 0x80, 0x80})
      -- One UTF-8 character
      eq({"\xf4\x80\x80\x80", 0x100000}, test_seq{0xf4, 0x80, 0x80, 0x80, 0xcc})

      -- Combining characters U+1AB0 and U+0301
      eq({"\xf4\x80\x80\x80\xe1\xaa\xb0\xcc\x81", 0x100000}, test_seq{0xf4, 0x80, 0x80, 0x80, 0xe1, 0xaa, 0xb0, 0xcc, 0x81})
    end)

  end)

end)