--[[
MIT License

Copyright (c) 2021 Tobias Enderle

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE.
--]]

local json = require("pyluatex-json")
local socket = require("socket")

pyluatex = pyluatex or {
    ignore_errors = false,
    verbose = false,
    session = "default"
}

-- status.filename: path to pyluatex.sty
local folder = file.pathpart(file.collapsepath(status.filename, true))
local script = file.join(folder, "pyluatex-interpreter.py")
local tcp = nil

local env_end = nil
local env_lines = nil
local parent_env = nil
local env_repl_mode = false

local last_code = nil
local last_output = nil

local function trim(s)
    return (s:gsub("^%s*(.-)%s*$", "%1"))
end

local function err_cmd(message)
    return "\\PackageError{PyLuaTeX}{" .. message .. "}{}"
end

function pyluatex.start(executable)
    local is_windows = package.config:sub(1,1) ~= "/"
    local cmd
    if is_windows then
        cmd = "start /B " .. executable .. " \"" .. script .. "\""
    else
        cmd = executable .. " \"" .. script .. "\" &"
    end
    local f = io.popen(cmd, "r")
    local port = f:read("*l"):gsub("\r", ""):gsub("\n", "")
    f:close()

    if port then
        tcp = socket.tcp()
        tcp:connect("127.0.0.1", port)
    else
        tex.sprint(err_cmd("Python backend (executable: " .. executable ..
                           ") could not be started"))
    end
end

local function request(data)
    tcp:send(json.encode(data) .. "\n")
    local output = tcp:receive("*l")
    local response = json.decode(output)
    return response.success, response.output
end

local function log_input(code)
    texio.write_nl("PyLuaTeX input for session \"" .. pyluatex.session .. "\": " .. code)
end

local function log_output(code)
    texio.write_nl("PyLuaTeX output: " .. code)
end

local function split_lines(str)
    if str:sub(-1) ~= "\n" then
        str = str .. "\n"
    end

    local t = {}
    for s in str:gmatch("(.-)\r?\n") do
        table.insert(t, s)
    end
    return t
end

function pyluatex.execute(code, auto_print, write, repl_mode)
    local full_code
    if auto_print then
        full_code = "print(str(" .. code .. "), end='')"
    else
        full_code = code
    end

    if pyluatex.verbose then log_input(full_code) end

    local success, output = request(
        {
            session = pyluatex.session,
            code = full_code,
            repl_mode = repl_mode,
            ignore_errors = pyluatex.ignore_errors
        }
    )
    last_code = split_lines(code)
    last_output = split_lines(output)

    if success or pyluatex.ignore_errors then
        if pyluatex.verbose or not success then log_output(output) end

        if write then
            tex.print(last_output)
        end
    else
        if not pyluatex.verbose then log_input(full_code) end
        log_output(output)
        if write then
            tex.sprint(err_cmd("Python error (see above)"))
        end
    end

    return success
end

function pyluatex.print_env()
    if last_output ~= nil then
        tex.print(last_output)
    end
end

local function record_line(line)
    local s, e = line:find(env_end, 1, true)
    if s ~= nil then
        luatexbase.remove_from_callback("process_input_buffer", "pyluatex_record_line")
        local code_in_line = line:sub(1, s - 1)
        if trim(code_in_line):len() > 0 then
            -- only include this line if it contains non-whitespace characters
            table.insert(env_lines, code_in_line)
        end
        local code = table.concat(env_lines, "\n")
        local success = pyluatex.execute(code, false, false, env_repl_mode)
        if success or pyluatex.ignore_errors then
            return line:sub(s)
        else
            return env_end .. err_cmd("Python error (see above)") .. line:sub(e + 1)
        end
    else
        table.insert(env_lines, line)
        return ""
    end
end

function pyluatex.record_env(name, repl_mode)
    if parent_env ~= nil then
        name = parent_env
        parent_env = nil
    end
    env_end = "\\end{" .. name .. "}"
    env_lines = {}
    env_repl_mode = repl_mode
    luatexbase.add_to_callback("process_input_buffer", record_line, "pyluatex_record_line")
end

function pyluatex.set_parent_env(name)
    if parent_env == nil then
        parent_env = name
    end
end

function pyluatex.run_file(path, write, repl_mode)
    local f = io.open(path, "r")
    if f then
        local code = f:read("*a")
        f:close()
        -- ignore trailing new line if present
        if code:sub(-2) == "\r\n" then
            code = code:sub(0, -3)
        elseif code:sub(-1) == "\n" then
            code = code:sub(0, -2)
        end
        pyluatex.execute(code, false, write, repl_mode)
    else
        tex.sprint(err_cmd("File not found: " .. path))
    end
end

function pyluatex.get_last_code()
    return last_code
end

function pyluatex.get_last_output()
    return last_output
end

local function parse_bool(name, value)
    if value == "true" then
        return true
    elseif value == "false" then
        return false
    else
        tex.sprint(
            err_cmd("Invalid value '" .. value .. "' for option " .. name)
        )
    end
end

function pyluatex.set_option(name, value)
    if name == "ignoreerrors" then
        pyluatex.ignore_errors = parse_bool(name, value)
    elseif name == "verbose" then
        pyluatex.verbose = parse_bool(name, value)
    else
        tex.sprint(err_cmd("Unknown option '" .. name .. "'"))
    end
end

return pyluatex
