require "crystal/at_exit_handlers"

{% unless flag?(:win32) %}
  require "c/unistd"
{% end %}

# The standard input file descriptor. Contains data piped to the program.
#
# On Unix systems, if the file descriptor is a TTY, the runtime duplicates it.
# So `STDIN.fd` might not be `0`.
# The reason for this is to enable non-blocking reads for concurrency. Other fibers
# can run while waiting on user input. The original file descriptor is
# inherited from the parent process. Setting it to non-blocking mode would
# reflect back, which can cause problems.
#
# On Windows, `STDIN` is always blocking.
STDIN = IO::FileDescriptor.from_stdio(0)

# The standard output file descriptor.
#
# Typically used to output data and information.
#
# At the start of the program STDOUT is configured like this:
# - if it's a TTY device (like the console) then `sync` is `true`,
#   meaning that output will be outputted as soon as it is written
#   to STDOUT. This is so users can see real time output data.
# - if it's not a TTY device (like a file, or because the output
#   was piped to a file) then `sync` is `false` but `flush_on_newline`
#   is `true`. This is so that if you pipe the output to a file, and,
#   for example, you `tail -f`, you can see data on a line-per-line basis.
#   This is convenient but slower than with `flush_on_newline` set to `false`.
#   If you need a bit more performance and you don't care about near real-time
#   output you can do `STDOUT.flush_on_newline = false`.
#
# On Unix systems, if the file descriptor is a TTY, the runtime duplicates it.
# So `STDOUT.fd` might not be `1`.
# The reason for this is to enable non-blocking writes for concurrency. Other fibers
# can run while waiting on IO. The original file descriptor is
# inherited from the parent process. Setting it to non-blocking mode would
# reflect back which can cause problems.
#
# On Windows, `STDOUT` is always blocking.
STDOUT = IO::FileDescriptor.from_stdio(1)

# The standard error file descriptor.
#
# Typically used to output error messages and diagnostics.
#
# At the start of the program STDERR is configured like this:
# - if it's a TTY device (like the console) then `sync` is `true`,
#   meaning that output will be outputted as soon as it is written
#   to STDERR. This is so users can see real time output data.
# - if it's not a TTY device (like a file, or because the output
#   was piped to a file) then `sync` is `false` but `flush_on_newline`
#   is `true`. This is so that if you pipe the output to a file, and,
#   for example, you `tail -f`, you can see data on a line-per-line basis.
#   This is convenient but slower than with `flush_on_newline` set to `false`.
#   If you need a bit more performance and you don't care about near real-time
#   output you can do `STDERR.flush_on_newline = false`.
#
# On Unix systems, if the file descriptor is a TTY, the runtime duplicates it.
# So `STDERR.fd` might not be `2`.
# The reason for this is to enable non-blocking writes for concurrency. Other fibers
# can run while waiting on IO. The original file descriptor is
# inherited from the parent process. Setting it to non-blocking mode would
# reflect back which can cause problems.
#
# On Windows, `STDERR` is always blocking.
STDERR = IO::FileDescriptor.from_stdio(2)

# The name, the program was called with.
#
# The result may be a relative or absolute path (including symbolic links),
# just the command name or the empty string.
#
# See `Process.executable_path` for a more convenient alternative that always
# returns the absolute real path to the executable file (if it exists).
PROGRAM_NAME = String.new(ARGV_UNSAFE.value)

# An array of arguments passed to the program.
ARGV = Array.new(ARGC_UNSAFE - 1) { |i| String.new(ARGV_UNSAFE[1 + i]) }

# An `IO` for reading files from `ARGV`.
#
# Usage example:
#
# `program.cr`:
# ```
# puts ARGF.gets_to_end
# ```
#
# A file to read from: (`file`)
# ```text
# 123
# ```
#
# ```text
# $ crystal build program.cr
# $ ./program file
# 123
# $ ./program file file
# 123123
# $ # If ARGV is empty, ARGF reads from STDIN instead:
# $ echo "hello" | ./program
# hello
# $ ./program unknown
# Unhandled exception: Error opening file with mode 'r': 'unknown': No such file or directory (File::NotFoundError)
# ...
# ```
#
# After a file from `ARGV` has been read, it's removed from `ARGV`.
#
# You can manipulate `ARGV` yourself to control what `ARGF` operates on.
# If you remove a file from `ARGV`, it is ignored by `ARGF`; if you add files to `ARGV`, `ARGF` will read from it.
#
# ```
# ARGV.replace ["file1"]
# ARGF.gets_to_end # => Content of file1
# ARGV             # => []
# ARGV << "file2"
# ARGF.gets_to_end # => Content of file2
# ```
ARGF = IO::ARGF.new(ARGV, STDIN)

# The newline constant
EOL = {% if flag?(:windows) %}
        "\r\n"
      {% else %}
        "\n"
      {% end %}

# Repeatedly executes the block.
#
# ```
# loop do
#   line = gets
#   break unless line
#   # ...
# end
# ```
def loop(&)
  while true
    yield
  end
end

# Reads a line from `STDIN`.
#
# See also: `IO#gets`.
def gets(*args, **options)
  STDIN.gets(*args, **options)
end

# Reads a line from `STDIN`.
#
# See also: `IO#read_line`.
def read_line(*args, **options)
  STDIN.read_line(*args, **options)
end

# Prints objects to `STDOUT` and then invokes `STDOUT.flush`.
#
# See also: `IO#print`.
def print(*objects : _) : Nil
  STDOUT.print *objects
end

# Prints a formatted string to `STDOUT`.
#
# For details on the format string, see `sprintf`.
def printf(format_string, *args) : Nil
  printf format_string, args
end

# :ditto:
def printf(format_string, args : Array | Tuple) : Nil
  STDOUT.printf format_string, args
end

# Returns a formatted string.
# The string is produced according to the *format_string* with format specifiers
# being replaced by values from *args* formatted according to the specifier.
#
# Within the format string, any characters other than format specifiers
# (specifiers beginning with `%`) are copied to the result. The formatter
# supports the following kinds of format specifiers:
#
# * Sequential (`%.1f`). The first `%` consumes the first argument, the second
#   consumes the second argument, and so on.
# * Positional (`%3$.1f`). The one-based argument index is specified as part of
#   the flags.
# * Named substitution (`%<name>.1f`, `%{name}`). The angle bracket form accepts
#   flags and the curly bracket form doesn't. Exactly one `Hash` or `NamedTuple`
#   must be passed as the argument.
#
# Mixing of different kinds of format specifiers is disallowed, except that the
# two named forms may be used together.
#
# A simple format specifier consists of a percent sign, followed by optional flags,
# width, and precision indicators, then terminated with a field type
# character.
#
# ```text
# %[flags][width][.precision]type
# ```
#
# A formatted substitution is similar but after the percent sign follows the
# mandatory name of the substitution wrapped in angle brackets.
#
# ```text
# %<name>[flags][width][.precision]type
# ```
#
# The percent sign itself is escaped by `%%`. No format modifiers are allowed,
# and no arguments are consumed.
#
# The field type controls how the corresponding argument value is to be
# interpreted, while the flags modify that interpretation.
#
# The field type characters are:
#
# ```text
# Field | Integer Format
# ------+------------------------------------------------------------------
#   b   | Formats argument as a binary number.
#   d   | Formats argument as a decimal number.
#   i   | Same as d.
#   o   | Formats argument as an octal number.
#   x   | Formats argument as a hexadecimal number using lowercase letters.
#   X   | Same as x, but uses uppercase letters.
#
# Field | Float Format
# ------+---------------------------------------------------------------
#   e   | Formats floating point argument into exponential notation
#       | with one digit before the decimal point as [-]d.dddddde[+-]dd.
#       | The precision specifies the number of digits after the decimal
#       | point (defaulting to six).
#   E   | Equivalent to e, but uses an uppercase E to indicate
#       | the exponent.
#   f   | Formats floating point argument as [-]ddd.dddddd,
#       | where the precision specifies the number of digits after
#       | the decimal point.
#   g   | Formats a floating point number using exponential form
#       | if the exponent is less than -4 or greater than or
#       | equal to the precision, or in dd.dddd form otherwise.
#       | The precision specifies the number of significant digits.
#   G   | Equivalent to g, but use an uppercase E in exponent form.
#   a   | Formats floating point argument as [-]0xh.hhhhp[+-]dd,
#       | which consists of an optional sign, "0x", fraction part
#       | as hexadecimal, "p", and exponential part as decimal.
#   A   | Equivalent to a, but uses uppercase X and P.
#
# Field | Other Format
# ------+------------------------------------------------------------
#   c   | Argument is a single character itself.
#   s   | Argument is a string to be substituted. If the format
#       | sequence contains a precision, at most that many characters
#       | will be copied.
# ```
#
# Flags modify the behavior of the format specifiers:
#
# ```text
# Flag     | Applies to    | Meaning
# ---------+---------------+----------------------------------------------------
# space    | bdiouxX       | Add a leading space character to
#          | aAeEfgG       | non-negative numbers. Has no effect if the plus
#          | (numeric fmt) | flag is also given.
# ---------+---------------+----------------------------------------------------
# #        | boxX          | Use an alternative format.
#          | aAeEfgG       | For x, X, b, prefix any non-zero result with
#          |               | 0x, 0X, or 0b respectively.
#          |               | For o, prefix any non-zero result with 0o. Note
#          |               | that this prefix is different from C and Ruby.
#          |               | For a, A, e, E, f, g, G,
#          |               | force a decimal point to be added,
#          |               | even if no digits follow.
#          |               | For g and G, do not remove trailing zeros.
# ---------+---------------+----------------------------------------------------
# +        | bdiouxX       | Add a leading plus sign to non-negative
#          | aAeEfgG       | numbers.
#          | (numeric fmt) |
# ---------+---------------+----------------------------------------------------
# -        | all           | Left-justify the result of this conversion.
# ---------+---------------+----------------------------------------------------
# 0 (zero) | bdiouxX       | Pad with zeros, not spaces. Has no effect if the
#          | aAeEfgG       | number is left-justified, or a precision is given
#          | (numeric fmt) | to an integer field type.
# ---------+---------------+----------------------------------------------------
# *        | all           | Use the next argument as the field width or
#          |               | precision. If width is negative, set the minus flag
#          |               | and use the argument's absolute value as field
#          |               | width. If precision is negative, it is ignored.
# ---------+---------------+----------------------------------------------------
# 1$ 2$ 3$ | all           | As a flag, specifies the one-based argument index
# ...      |               | for a positional format specifier.
#          |               | Immediately after *, use the argument at the given
#          |               | one-based index as the width or precision, instead
#          |               | of the next argument. The entire format string must
#          |               | also use positional format specifiers throughout.
# ```
#
# Examples of flags:
#
# Decimal number conversion:
# ```
# sprintf "%d", 123  # => "123"
# sprintf "%+d", 123 # => "+123"
# sprintf "% d", 123 # => " 123"
# ```
#
# Octal number conversion:
# ```
# sprintf "%o", 123   # => "173"
# sprintf "%+o", 123  # => "+173"
# sprintf "%o", -123  # => "-173"
# sprintf "%+o", -123 # => "-173"
# ```
#
# Hexadecimal number conversion:
# ```
# sprintf "%x", 123   # => "7b"
# sprintf "%+x", 123  # => "+7b"
# sprintf "%x", -123  # => "-7b"
# sprintf "%+x", -123 # => "-7b"
# sprintf "%#x", 0    # => "0"
# sprintf "% x", 123  # => " 7b"
# sprintf "% x", -123 # => "-7b"
# sprintf "%X", 123   # => "7B"
# sprintf "%#X", -123 # => "-0X7B"
# ```
#
# Binary number conversion:
# ```
# sprintf "%b", 123    # => "1111011"
# sprintf "%+b", 123   # => "+1111011"
# sprintf "%+b", -123  # => "-1111011"
# sprintf "%b", -123   # => "-1111011"
# sprintf "%#b", 0     # => "0"
# sprintf "% b", 123   # => " 1111011"
# sprintf "%+ b", 123  # => "+1111011"
# sprintf "% b", -123  # => "-1111011"
# sprintf "%+ b", -123 # => "-1111011"
# sprintf "%#b", 123   # => "0b1111011"
# ```
#
# Floating point conversion:
# ```
# sprintf "%a", 123 # => "0x1.ecp+6"
# sprintf "%A", 123 # => "0X1.ECP+6"
# ```
#
# Exponential form conversion:
# ```
# sprintf "%g", 123.4          # => "123.4"
# sprintf "%g", 123.4567       # => "123.457"
# sprintf "%20.8g", 1234.56789 # => "           1234.5679"
# sprintf "%20.8g", 123456789  # => "       1.2345679e+08"
# sprintf "%20.8G", 123456789  # => "       1.2345679E+08"
# sprintf "%20.8g", -123456789 # => "      -1.2345679e+08"
# sprintf "%20.8G", -123456789 # => "      -1.2345679E+08"
# ```
#
# The field width is an optional integer, followed optionally by a
# period and a precision. The width specifies the minimum number of
# characters that will be written to the result for this field.
#
# Examples of width:
# ```
# sprintf "%20d", 123   # => "                 123"
# sprintf "%+20d", 123  # => "                +123"
# sprintf "%020d", 123  # => "00000000000000000123"
# sprintf "%+020d", 123 # => "+0000000000000000123"
# sprintf "% 020d", 123 # => " 0000000000000000123"
# sprintf "%-20d", 123  # => "123                 "
# sprintf "%-+20d", 123 # => "+123                "
# sprintf "%- 20d", 123 # => " 123                "
# sprintf "%020x", -123 # => "-000000000000000007b"
# sprintf "%020X", -123 # => "-000000000000000007B"
# ```
#
# For numeric fields, the precision controls the number of decimal places
# displayed.
#
# For string fields, the precision determines the maximum
# number of characters to be copied from the string.
#
# Examples of precisions:
#
# Precision for `d`, `o`, `x` and `b` is
# minimum number of digits:
# ```
# sprintf "%20.8d", 123   # => "            00000123"
# sprintf "%020.8d", 123  # => "            00000123"
# sprintf "%20.8o", 123   # => "            00000173"
# sprintf "%020.8o", 123  # => "            00000173"
# sprintf "%20.8x", 123   # => "            0000007b"
# sprintf "%020.8x", 123  # => "            0000007b"
# sprintf "%20.8b", 123   # => "            01111011"
# sprintf "%20.8d", -123  # => "           -00000123"
# sprintf "%020.8d", -123 # => "           -00000123"
# sprintf "%20.8o", -123  # => "           -00000173"
# sprintf "%20.8x", -123  # => "           -0000007b"
# sprintf "%20.8b", -11   # => "           -00001011"
# ```
#
# Precision for `e` is number of digits after the decimal point:
# ```
# sprintf "%20.8e", 1234.56789 # => "      1.23456789e+03"
# ```
#
# Precision for `f` is number of digits after the decimal point:
# ```
# sprintf "%20.8f", 1234.56789 # => "       1234.56789000"
# ```
#
# Precision for `g` is number of significant digits:
# ```
# sprintf "%20.8g", 1234.56789 # => "           1234.5679"
# sprintf "%20.8g", 123456789  # => "       1.2345679e+08"
# sprintf "%-20.8g", 123456789 # => "1.2345679e+08       "
# ```
#
# Precision for `s` is maximum number of characters:
# ```
# sprintf "%20.8s", "string test" # => "            string t"
# ```
#
# Additional examples:
# ```
# sprintf "%d %04x", 123, 123                 # => "123 007b"
# sprintf "%08b '%4s'", 123, 123              # => "01111011 ' 123'"
# sprintf "%+g:% g:%-g", 1.23, 1.23, 1.23     # => "+1.23: 1.23:1.23"
# sprintf "%-3$*1$.*2$s", 10, 5, "abcdefghij" # => "abcde     "
# ```
def sprintf(format_string, *args) : String
  sprintf format_string, args
end

# :ditto:
def sprintf(format_string, args : Array | Tuple) : String
  String.build(format_string.bytesize) do |str|
    String::Formatter(typeof(args)).new(format_string, args, str).format
  end
end

# Prints *objects* to `STDOUT`, each followed by a newline character unless
# the object is a `String` and already ends with a newline.
#
# See also: `IO#puts`.
def puts(*objects) : Nil
  STDOUT.puts *objects
end

# Inspects *object* to `STDOUT` followed
# by a newline. Returns *object*.
#
# See also: `Object#inspect(io)`.
def p(object)
  object.inspect(STDOUT)
  puts
  object
end

# Inspects each object in *objects* to `STDOUT`, followed
# by a newline. Returns *objects*.
#
# See also: `Object#inspect(io)`.
def p(*objects)
  objects.each do |obj|
    p obj
  end
  objects
end

# Inspects *objects* to `STDOUT`, followed
# by a newline. Returns *objects*.
#
# ```
# p foo: 23, bar: 42 # => {foo: 23, bar: 42}
# ```
#
# See `Object#inspect(io)`
def p(**objects)
  p(objects) unless objects.empty?
end

# Pretty prints *object* to `STDOUT` followed
# by a newline. Returns *object*.
#
# See also: `Object#pretty_print(pp)`.
def pp(object)
  PrettyPrint.format(object, STDOUT, 79)
  puts
  object
end

# Pretty prints each object in *objects* to `STDOUT`, followed
# by a newline. Returns *objects*.
#
# See also: `Object#pretty_print(pp)`.
def pp(*objects)
  objects.each do |obj|
    pp obj
  end
  objects
end

# Pretty prints *objects* to `STDOUT`, followed
# by a newline. Returns *objects*.
#
# ```
# p foo: 23, bar: 42 # => {foo: 23, bar: 42}
# ```
#
# See `Object#pretty_print(pp)`
def pp(**objects)
  pp(objects) unless objects.empty?
end

# Registers the given `Proc` for execution when the program exits regularly.
#
# A regular exit happens when either
# * the main fiber reaches the end of the program,
# * the main fiber rescues an unhandled exception, or
# * `::exit` is called.
#
# `Process.exit` does *not* trigger `at_exit` handlers, nor does external process
# termination (see `Process.on_terminate` for handling that).
#
# If multiple handlers are registered, they are executed in reverse order of registration.
#
# ```
# def do_at_exit(str1)
#   at_exit { print str1 }
# end
#
# at_exit { puts "cruel world" }
# do_at_exit("goodbye ")
# exit
# ```
#
# Produces:
#
# ```text
# goodbye cruel world
# ```
#
# The exit status code that will be returned by this program is passed to
# the block as its first argument. In case of any unhandled exception, it is
# passed as the second argument to the block, if the program terminates
# normally or `exit(status)` is called explicitly, then the second argument
# will be `nil`.
#
# NOTE: If `at_exit` is called inside an `at_exit` handler, it will be called
# right after the current `at_exit` handler ends, and then other handlers
# will be invoked.
def at_exit(&handler : Int32, Exception? ->) : Nil
  Crystal::AtExitHandlers.add(handler)
end

# Terminates execution immediately, returning the given status code
# to the invoking environment.
#
# Registered `at_exit` procs are executed.
def exit(status = 0) : NoReturn
  status = Crystal::AtExitHandlers.run status
  Crystal.ignore_stdio_errors { STDOUT.flush }
  Crystal.ignore_stdio_errors { STDERR.flush }
  Process.exit(status)
end

# Terminates execution immediately, printing *message* to `STDERR` and
# then calling `exit(status)`.
def abort(message = nil, status = 1) : NoReturn
  Crystal.ignore_stdio_errors { STDERR.puts message } if message
  exit status
end

{% if !flag?(:preview_mt) && flag?(:unix) %}
  class Process
    # :nodoc:
    #
    # Hooks are defined here due to load order problems.
    def self.after_fork_child_callbacks
      @@after_fork_child_callbacks ||= [
        # clean ups (don't depend on event loop):
        ->Crystal::System::Signal.after_fork,
        ->Crystal::System::SignalChildHandler.after_fork,

        # reinit event loop:
        ->{ Crystal::EventLoop.current.after_fork },

        # more clean ups (may depend on event loop):
        ->Random::DEFAULT.new_seed,
      ] of -> Nil
    end
  end
{% end %}

{% unless flag?(:interpreted) || flag?(:wasm32) %}
  # load debug info on start up of the program is executed with CRYSTAL_LOAD_DEBUG_INFO=1
  # this will make debug info available on print_frame that is used by Crystal's segfault handler
  #
  # - CRYSTAL_LOAD_DEBUG_INFO=0 will never use debug info (See Exception::CallStack.load_debug_info)
  # - CRYSTAL_LOAD_DEBUG_INFO=1 will load debug info on startup
  # - Other values will load debug info on demand: when the backtrace of the first exception is generated
  Exception::CallStack.load_debug_info if ENV["CRYSTAL_LOAD_DEBUG_INFO"]? == "1"
  Exception::CallStack.setup_crash_handler

  Crystal::Scheduler.init

  {% if flag?(:win32) %}
    Crystal::System::Process.start_interrupt_loop
  {% else %}
    Crystal::System::Signal.setup_default_handlers
  {% end %}
{% end %}
