if SERVER then
    AddCSLuaFile("utf8data.lua")
end
include("utf8data.lua")

-- Copyright (c) 2006-2007, Kyle Smith

-- returns the number of bytes used by the UTF-8 character at byte i in s
-- also doubles as a UTF-8 character validator
local function utf8charbytes(s, i)
    -- argument defaults
    i = i or 1

    -- argument checking
    if type(s) ~= "string" then
        error("bad argument #1 to 'utf8charbytes' (string expected, got ".. type(s).. ")")
    end
    if type(i) ~= "number" then
        error("bad argument #2 to 'utf8charbytes' (number expected, got ".. type(i).. ")")
    end

    local c = s:byte(i)

    -- determine bytes needed for character, based on RFC 3629
    -- validate byte 1
    if c > 0 and c <= 127 then
        -- UTF8-1
        return 1
    elseif c >= 194 and c <= 223 then
        -- UTF8-2
        local c2 = s:byte(i + 1)

        if not c2 then
            error("UTF-8 string terminated early")
        end

        -- validate byte 2
        if c2 < 128 or c2 > 191 then
            error("Invalid UTF-8 character")
        end

        return 2
    elseif c >= 224 and c <= 239 then
        -- UTF8-3
        local c2 = s:byte(i + 1)
        local c3 = s:byte(i + 2)

        if not c2 or not c3 then
            error("UTF-8 string terminated early")
        end

        -- validate byte 2
        if c == 224 and (c2 < 160 or c2 > 191) then
            error("Invalid UTF-8 character")
        elseif c == 237 and (c2 < 128 or c2 > 159) then
            error("Invalid UTF-8 character")
        elseif c2 < 128 or c2 > 191 then
            error("Invalid UTF-8 character")
        end

        -- validate byte 3
        if c3 < 128 or c3 > 191 then
            error("Invalid UTF-8 character")
        end

        return 3
    elseif c >= 240 and c <= 244 then
        -- UTF8-4
        local c2 = s:byte(i + 1)
        local c3 = s:byte(i + 2)
        local c4 = s:byte(i + 3)

        if not c2 or not c3 or not c4 then
            error("UTF-8 string terminated early")
        end

        -- validate byte 2
        if c == 240 and (c2 < 144 or c2 > 191) then
            error("Invalid UTF-8 character")
        elseif c == 244 and (c2 < 128 or c2 > 143) then
            error("Invalid UTF-8 character")
        elseif c2 < 128 or c2 > 191 then
            error("Invalid UTF-8 character")
        end

        -- validate byte 3
        if c3 < 128 or c3 > 191 then
            error("Invalid UTF-8 character")
        end

        -- validate byte 4
        if c4 < 128 or c4 > 191 then
            error("Invalid UTF-8 character")
        end

        return 4
    else
        error("Invalid UTF-8 character")
    end
end

-- returns the number of characters in a UTF-8 string
local function utf8len(s)
    -- argument checking
    if type(s) ~= "string" then
        error("bad argument #1 to 'utf8len' (string expected, got ".. type(s).. ")")
    end

    local pos = 1
    local bytes = s:len()
    local len = 0

    while pos <= bytes do
        len = len + 1
        pos = pos + utf8charbytes(s, pos)
    end

    return len
end
string.utf8len = utf8len

-- functions identically to string.sub except that i and j are UTF-8 characters
-- instead of bytes
local function utf8sub(s, i, j)
    -- argument defaults
    j = j or -1

    -- argument checking
    if type(s) ~= "string" then
        error("bad argument #1 to 'utf8sub' (string expected, got ".. type(s).. ")")
    end
    if type(i) ~= "number" then
        error("bad argument #2 to 'utf8sub' (number expected, got ".. type(i).. ")")
    end
    if type(j) ~= "number" then
        error("bad argument #3 to 'utf8sub' (number expected, got ".. type(j).. ")")
    end

    local pos = 1
    local bytes = s:len()
    local len = 0

    -- only set l if i or j is negative
    local l = (i >= 0 and j >= 0) or s:utf8len()
    local startChar = i >= 0 and i or l + i + 1
    local endChar   = j >= 0 and j or l + j + 1

    -- can't have start before end!
    if startChar > endChar then
        return ""
    end

    -- byte offsets to pass to string.sub
    local startByte, endByte = 1, bytes

    while pos <= bytes do
        len = len + 1

        if len == startChar then
            startByte = pos
        end

        pos = pos + utf8charbytes(s, pos)

        if len == endChar then
            endByte = pos - 1
            break
        end
    end

    return s:sub(startByte, endByte)
end
string.utf8sub = utf8sub

-- replace UTF-8 characters based on a mapping table
local function utf8replace(s, mapping)
    -- argument checking
    if type(s) ~= "string" then
        error("bad argument #1 to 'utf8replace' (string expected, got ".. type(s).. ")")
    end
    if type(mapping) ~= "table" then
        error("bad argument #2 to 'utf8replace' (table expected, got ".. type(mapping).. ")")
    end

    local pos = 1
    local bytes = s:len()
    local charbytes
    local newstr = ""

    while pos <= bytes do
        charbytes = utf8charbytes(s, pos)
        local c = s:sub(pos, pos + charbytes - 1)

        newstr = newstr .. (mapping[c] or c)

        pos = pos + charbytes
    end

    return newstr
end

-- identical to string.upper except it knows about unicode simple case conversions
local function utf8upper(s)
    return utf8replace(s, utf8_lc_uc)
end
if utf8_lc_uc then
    string.utf8upper = utf8upper
end

-- identical to string.lower except it knows about unicode simple case conversions
local function utf8lower(s)
    return utf8replace(s, utf8_uc_lc)
end
if utf8_uc_lc then
    string.utf8lower = utf8lower
end

-- identical to string.reverse except that it supports UTF-8
local function utf8reverse(s)
    -- argument checking
    if type(s) ~= "string" then
        error("bad argument #1 to 'utf8reverse' (string expected, got ".. type(s).. ")")
    end

    local bytes = s:len()
    local pos = bytes
    local charbytes
    local newstr = ""

    while pos > 0 do
        c = s:byte(pos)
        while c >= 128 and c <= 191 do
            pos = pos - 1
            c = s:byte(pos)
        end

        charbytes = utf8charbytes(s, pos)

        newstr = newstr .. s:sub(pos, pos + charbytes - 1)

        pos = pos - 1
    end

    return newstr
end
string.utf8reverse = utf8reverse