-- json.lua: High-performance JSON module for Moonshark
local json = {}

function json.go_encode(value)
    return __json_marshal(value)
end

function json.go_decode(str)
    if type(str) ~= "string" then
        error("json.decode: expected string, got " .. type(str), 2)
    end
    return __json_unmarshal(str)
end

function json.encode(data)
	local t = type(data)

	if t == "nil" then return "null" end
	if t == "boolean" then return data and "true" or "false" end
	if t == "number" then return tostring(data) end

	if t == "string" then
		local escape_chars = {
			['"'] = '\\"', ['\\'] = '\\\\',
			['\n'] = '\\n', ['\r'] = '\\r', ['\t'] = '\\t'
		}
		return '"' .. data:gsub('[\\"\n\r\t]', escape_chars) .. '"'
	end

	if t == "table" then
		local isArray = true
		local count = 0
		local max_index = 0

		for k, _ in pairs(data) do
			count = count + 1
			if type(k) == "number" and k > 0 and math.floor(k) == k then
			max_index = math.max(max_index, k)
			else
			isArray = false
			break
			end
		end

		local result = {}

		if isArray then
			for i, v in ipairs(data) do
			result[i] = json.encode(v)
			end
			return "[" .. table.concat(result, ",") .. "]"
		else
			local size = 0
			for k, v in pairs(data) do
			if type(k) == "string" and type(v) ~= "function" and type(v) ~= "userdata" then
				size = size + 1
			end
			end

			result = {}
			local index = 1
			for k, v in pairs(data) do
			if type(k) == "string" and type(v) ~= "function" and type(v) ~= "userdata" then
				result[index] = json.encode(k) .. ":" .. json.encode(v)
				index = index + 1
			end
			end
			return "{" .. table.concat(result, ",") .. "}"
		end
	end

	return "null"  -- Unsupported type
end

function json.decode(data)
	local pos = 1
	local len = #data

	-- Pre-compute byte values
	local b_space = string.byte(' ')
	local b_tab = string.byte('\t')
	local b_cr = string.byte('\r')
	local b_lf = string.byte('\n')
	local b_quote = string.byte('"')
	local b_backslash = string.byte('\\')
	local b_slash = string.byte('/')
	local b_lcurly = string.byte('{')
	local b_rcurly = string.byte('}')
	local b_lbracket = string.byte('[')
	local b_rbracket = string.byte(']')
	local b_colon = string.byte(':')
	local b_comma = string.byte(',')
	local b_0 = string.byte('0')
	local b_9 = string.byte('9')
	local b_minus = string.byte('-')
	local b_plus = string.byte('+')
	local b_dot = string.byte('.')
	local b_e = string.byte('e')
	local b_E = string.byte('E')

	-- Skip whitespace more efficiently
	local function skip()
	  local b
	  while pos <= len do
		b = data:byte(pos)
		if b > b_space or (b ~= b_space and b ~= b_tab and b ~= b_cr and b ~= b_lf) then
		  break
		end
		pos = pos + 1
	  end
	end

	-- Forward declarations
	local parse_value, parse_string, parse_number, parse_object, parse_array

	-- Parse a string more efficiently
	parse_string = function()
	  pos = pos + 1  -- Skip opening quote

	  if pos > len then
		error("Unterminated string")
	  end

	  -- Use a table to build the string
	  local result = {}
	  local result_pos = 1
	  local start = pos
	  local c, b

	  while pos <= len do
		b = data:byte(pos)

		if b == b_backslash then
		  -- Add the chunk before the escape character
		  if pos > start then
			result[result_pos] = data:sub(start, pos - 1)
			result_pos = result_pos + 1
		  end

		  pos = pos + 1
		  if pos > len then
			error("Unterminated string escape")
		  end

		  c = data:byte(pos)
		  if c == b_quote then
			result[result_pos] = '"'
		  elseif c == b_backslash then
			result[result_pos] = '\\'
		  elseif c == b_slash then
			result[result_pos] = '/'
		  elseif c == string.byte('b') then
			result[result_pos] = '\b'
		  elseif c == string.byte('f') then
			result[result_pos] = '\f'
		  elseif c == string.byte('n') then
			result[result_pos] = '\n'
		  elseif c == string.byte('r') then
			result[result_pos] = '\r'
		  elseif c == string.byte('t') then
			result[result_pos] = '\t'
		  else
			result[result_pos] = data:sub(pos, pos)
		  end

		  result_pos = result_pos + 1
		  pos = pos + 1
		  start = pos
		elseif b == b_quote then
		  -- Add the final chunk
		  if pos > start then
			result[result_pos] = data:sub(start, pos - 1)
			result_pos = result_pos + 1
		  end

		  pos = pos + 1
		  return table.concat(result)
		else
		  pos = pos + 1
		end
	  end

	  error("Unterminated string")
	end

	-- Parse a number more efficiently
	parse_number = function()
	  local start = pos
	  local b = data:byte(pos)

	  -- Skip any sign
	  if b == b_minus then
		pos = pos + 1
		if pos > len then
		  error("Malformed number")
		end
		b = data:byte(pos)
	  end

	  -- Integer part
	  if b < b_0 or b > b_9 then
		error("Malformed number")
	  end

	  repeat
		pos = pos + 1
		if pos > len then break end
		b = data:byte(pos)
	  until b < b_0 or b > b_9

	  -- Fractional part
	  if pos <= len and b == b_dot then
		pos = pos + 1
		if pos > len or data:byte(pos) < b_0 or data:byte(pos) > b_9 then
		  error("Malformed number")
		end

		repeat
		  pos = pos + 1
		  if pos > len then break end
		  b = data:byte(pos)
		until b < b_0 or b > b_9
	  end

	  -- Exponent
	  if pos <= len and (b == b_e or b == b_E) then
		pos = pos + 1
		if pos > len then
		  error("Malformed number")
		end

		b = data:byte(pos)
		if b == b_plus or b == b_minus then
		  pos = pos + 1
		  if pos > len then
			error("Malformed number")
		  end
		  b = data:byte(pos)
		end

		if b < b_0 or b > b_9 then
		  error("Malformed number")
		end

		repeat
		  pos = pos + 1
		  if pos > len then break end
		  b = data:byte(pos)
		until b < b_0 or b > b_9
	  end

	  return tonumber(data:sub(start, pos - 1))
	end

	-- Parse an object more efficiently
	parse_object = function()
	  pos = pos + 1  -- Skip opening brace
	  local obj = {}

	  skip()
	  if pos <= len and data:byte(pos) == b_rcurly then
		pos = pos + 1
		return obj
	  end

	  while pos <= len do
		skip()

		if data:byte(pos) ~= b_quote then
		  error("Expected string key")
		end

		local key = parse_string()
		skip()

		if data:byte(pos) ~= b_colon then
		  error("Expected colon")
		end
		pos = pos + 1

		obj[key] = parse_value()
		skip()

		local b = data:byte(pos)
		if b == b_rcurly then
		  pos = pos + 1
		  return obj
		end

		if b ~= b_comma then
		  error("Expected comma or closing brace")
		end
		pos = pos + 1
	  end

	  error("Unterminated object")
	end

	-- Parse an array more efficiently
	parse_array = function()
	  pos = pos + 1  -- Skip opening bracket
	  local arr = {}
	  local index = 1

	  skip()
	  if pos <= len and data:byte(pos) == b_rbracket then
		pos = pos + 1
		return arr
	  end

	  while pos <= len do
		arr[index] = parse_value()
		index = index + 1

		skip()

		local b = data:byte(pos)
		if b == b_rbracket then
		  pos = pos + 1
		  return arr
		end

		if b ~= b_comma then
		  error("Expected comma or closing bracket")
		end
		pos = pos + 1
	  end

	  error("Unterminated array")
	end

	-- Parse a value more efficiently
	parse_value = function()
	  skip()

	  if pos > len then
		error("Unexpected end of input")
	  end

	  local b = data:byte(pos)

	  if b == b_quote then
		return parse_string()
	  elseif b == b_lcurly then
		return parse_object()
	  elseif b == b_lbracket then
		return parse_array()
	  elseif b == string.byte('n') and pos + 3 <= len and data:sub(pos, pos + 3) == "null" then
		pos = pos + 4
		return nil
	  elseif b == string.byte('t') and pos + 3 <= len and data:sub(pos, pos + 3) == "true" then
		pos = pos + 4
		return true
	  elseif b == string.byte('f') and pos + 4 <= len and data:sub(pos, pos + 4) == "false" then
		pos = pos + 5
		return false
	  elseif b == b_minus or (b >= b_0 and b <= b_9) then
		return parse_number()
	  else
		error("Unexpected character: " .. string.char(b))
	  end
	end

	skip()
	local result = parse_value()
	skip()

	if pos <= len then
	  error("Unexpected trailing characters")
	end

	return result
end

function json.is_valid(str)
    if type(str) ~= "string" then return false end
    local status, _ = pcall(json.decode, str)
    return status
end

function json.pretty_print(value)
    if type(value) == "string" then
        value = json.decode(value)
    end

    local function stringify(val, indent, visited)
        visited = visited or {}
        indent = indent or 0
        local spaces = string.rep("  ", indent)

        if type(val) == "table" then
            if visited[val] then return "{...}" end
            visited[val] = true

            local isArray = true
            local i = 1
            for k in pairs(val) do
                if type(k) ~= "number" or k ~= i then
                    isArray = false
                    break
                end
                i = i + 1
            end

            local result = isArray and "[\n" or "{\n"
            local first = true

            if isArray then
                for i, v in ipairs(val) do
                    if not first then result = result .. ",\n" end
                    first = false
                    result = result .. spaces .. "  " .. stringify(v, indent + 1, visited)
                end
            else
                for k, v in pairs(val) do
                    if not first then result = result .. ",\n" end
                    first = false
                    result = result .. spaces .. "  \"" .. tostring(k) .. "\": " .. stringify(v, indent + 1, visited)
                end
            end

            return result .. "\n" .. spaces .. (isArray and "]" or "}")
        elseif type(val) == "string" then
            return "\"" .. val:gsub('\\', '\\\\'):gsub('"', '\\"'):gsub('\n', '\\n') .. "\""
        else
            return tostring(val)
        end
    end

    return stringify(value)
end

return json