#!/usr/bin/python3

from argparse import ArgumentParser
from os import system, environ, makedirs
from os.path import exists, join as path_join
from sys import stdin, exit
from typing import Dict, Union
import subprocess

# Paths
PATHS = {
	"src_dir": "src",
	"build_dir": "build",
	"template": "template.c",
	"substitute": "substituted.c",
	"output": "render_bytebeat",
	"fwrite_le_header": "fwrite_le.h",
	"fwrite_le": "fwrite_le.c",
	"include_directory": "include"
}

# Resolve paths
PATHS["template"] = path_join(PATHS["src_dir"], PATHS["template"])
PATHS["substitute"] = path_join(PATHS["build_dir"], PATHS["substitute"])
PATHS["output"] = path_join(PATHS["build_dir"], PATHS["output"])
PATHS["fwrite_le"] = path_join(PATHS["src_dir"], PATHS["fwrite_le"])

# Add `.` directory before all paths for compilation
PATHS["template"] = path_join(".", PATHS["template"])
PATHS["substitute"] = path_join(".", PATHS["substitute"])
PATHS["output"] = path_join(".", PATHS["output"])
PATHS["fwrite_le"] = path_join(".", PATHS["fwrite_le"])
PATHS["include_directory"] = path_join(".", PATHS["include_directory"])

# Default parameters
DEFAULT_PARAMETERS = {
	"CC": "cc",
	"CFLAGS": "-Ofast -march=native -mtune=native -Wall -Wextra -Wpedantic "
	          "-pedantic -Wno-unused-variable -Wno-unused-but-set-variable "
	          "-Wno-dangling-else -Wno-parentheses -std=c99",
	"INPUT_FILE": PATHS["substitute"],
	"OUTPUT_FILE": PATHS["output"]
}

def fetch(name: str):
	if from_env := environ.get(name):
		return from_env
	elif name != "CFLAGS_EXTRA":
		return DEFAULT_PARAMETERS[name]

def read_file(path: str) -> str:
	return open(path, "r", encoding="utf-8-sig").read()

def rewrite_file(path: str, content: str):
	return open(path, "w", encoding="utf-8").write(content)

def read_from_file_or_stdin(path: str) -> str:
	if path == "-":
		return "\n".join(stdin)
	elif exists(path):
		return read_file(path)
	else:
		print("The specified file doesn't exist")
		raise SystemExit

def substitute_vars(replacements: Dict[str, Union[bool, str]], text: str,
                    verbose: bool) -> str:
	if verbose:
		print("Substituting values:")
	for placeholder, replacement in replacements.items():
		if isinstance(replacement, bool):
			replacement = preprocessor_bool(replacement)

		if verbose and placeholder != "bytebeat_contents":
			print(placeholder, ": ", replacement, sep="")
		text = text.replace(f"`{placeholder}`", str(replacement))
	if verbose:
		print()
	return text

preprocessor_bool = lambda value: "1" if value else "0"
C_str_repr = lambda s: '"' + s.replace("\\", "\\\\").replace(r'"', r'\"') + '"'

CC = fetch("CC")
CFLAGS = fetch("CFLAGS")
INPUT_FILE = fetch("INPUT_FILE")
OUTPUT_FILE = fetch("OUTPUT_FILE")
if extra := fetch("CFLAGS_EXTRA"):
	CFLAGS += " " + extra

if __name__ == "__main__":
	parser = ArgumentParser(description=\
		"Substitutes supplied C (non-JavaScript!) bytebeat into the template, "
		"then attempts to compile the instance of the template. Accepts "
		"environmental variables `CC`, `CFLAGS`, `INPUT_FILE`, `OUTPUT_FILE`. "
		"`CFLAGS_EXTRA` can be used to add to default `CFLAGS`.")
	parser.add_argument("file", type=str,
		help="bytebeat formula file (use `-` to read from stdin)")
	parser.add_argument("-o", "--output", default="output.wav", type=str,
		help="specify output file path (default is `output.wav`")
	parser.add_argument("-r", "--sample-rate", default=8000, type=int,
		help="sample rate (Hz)")
	parser.add_argument("-p", "--final-sample-rate", default=None, type=int,
		help="convert the output to a different sample rate (usually one that "
		"is set in the system, to improve sound quality) during generation "
		"(not just reinterpretation)")
	parser.add_argument("-b", "--bit-depth", default=8, type=int,
		help="bit depth")
	parser.add_argument("-s", "--signed", default=False, action="store_true",
		help="is signed?")
	parser.add_argument("-R", "--precalculate-ratio", default=False,
		action="store_true",
		help="precalculate sample ratio to speed up rendering (may produce "
		     "inaccurate results")
	parser.add_argument("-m", "--faster-sample-ratio-math", default=False,
		action="store_true",
		help="faster sample ratio math (implies argument -R)")
	parser.add_argument("-f", "--floating-point", default=False,
		action="store_true", help="use floating point as the return type")
	parser.add_argument("-c", "--channels", default=1, type=int,
		help="amount of channels")
	parser.add_argument("-t", "--seconds", default=None, type=int,
		help="length in seconds (samples = sample rate * seconds) : "
		     "default = 30 seconds")
	parser.add_argument("-l", "--samples", default=None, type=int,
		help="length in samples (adds to `-t`; supports negative numbers) : "
			 "default = +0 samples")
	parser.add_argument("-a", "--no-return", default=False, action="store_true",
		help="do not insert return statement before the code")
	parser.add_argument("-u", "--mode", default="sequential", type=str,
		help="mode of writing: `sequential` or `instant` (the latter is not "
		     "recommended, since the whole result would be stored in RAM)")
	parser.add_argument("-n", "--block-size", default=65536, type=int,
		help="sequential mode only: block size of each sequence, bytes")
	parser.add_argument("-q", "--silent", default=False, action="store_true",
		help="do not output anything during generation")
	parser.add_argument("-v", "--verbose", default=False, action="store_true",
		help="show progress during generation")
	parser.add_argument("-E", "--show-substituted-values", default=False,
		action="store_true", help="show substituted values")
	args = parser.parse_args()

	bytebeat_contents = read_from_file_or_stdin(args.file).strip()

	if not bytebeat_contents:
		print("No valid contents")
		raise SystemExit

	# - Compilation
	makedirs(PATHS["build_dir"], exist_ok=True)

	if not args.no_return:  # Insert `return` statement
		# XXX: The bytebeat code is enclosed in parentheses to allow for the
		# use of commas as a comma operator, enabling more formulas to function.
		bytebeat_contents = f"return ({bytebeat_contents})"

	original_sample_rate = args.sample_rate
	final_sample_rate_code = ""
	if args.faster_sample_ratio_math:
		args.precalculate_ratio = True
	if args.precalculate_ratio and not args.final_sample_rate is None:
		if args.faster_sample_ratio_math:
			sample_rate_ratio = args.sample_rate / args.final_sample_rate
			final_sample_rate_code = f"w *= {sample_rate_ratio}L;"
		else:
			sample_rate_ratio = args.final_sample_rate / args.sample_rate
			final_sample_rate_code = f"w /= {sample_rate_ratio}L;"
		args.sample_rate = args.final_sample_rate

	final_sample_rate = \
		value if (value := args.final_sample_rate) else original_sample_rate
	samples = 0
	while True:
		no_seconds = args.seconds is None or args.seconds == 0
		no_samples = args.samples is None or args.samples == 0
		seconds_specified = not no_seconds
		samples_specified = not no_samples

		if seconds_specified and args.seconds < 0:
			print("CLI: Count of seconds can't be less than zero.")
			raise SystemExit

		if no_seconds and samples_specified:
			samples = args.samples
		elif seconds_specified and samples_specified:
			samples = args.seconds * final_sample_rate + args.samples
		elif seconds_specified and no_samples:
			samples = args.seconds * final_sample_rate
		elif no_seconds and no_samples:
			args.seconds = 30  # default
			continue
		else:
			print("CLI: Incorrect seconds/samples length format.")
			raise SystemExit
		break

	if samples <= 0:
		print("CLI: Count of samples should be greater than zero.")
		raise SystemExit

	if args.mode != "sequential" and args.mode != "instant":
		print("Invalid mode '%s'" % args.mode)
		raise SystemExit

	gen_length = args.channels * samples

	rewrite_file(PATHS["substitute"], substitute_vars({
		"bytebeat_contents": bytebeat_contents,
		"output_file": C_str_repr(args.output),
		"sample_rate": \
			value if (value := args.final_sample_rate) else args.sample_rate,
		"original_sample_rate": original_sample_rate,
		"final_sample_rate_code": final_sample_rate_code,
		"bit_depth": args.bit_depth,
		"is_signed": args.signed,
		"precalculated_ratio": args.precalculate_ratio,
		"faster_sample_ratio_math": args.precalculate_ratio,
		"fp_return_type": args.floating_point,
		"channels": args.channels,
		"length": samples,
		"wav_product": gen_length * (args.bit_depth // 8),
		"gen_length": gen_length,
		"sequential_mode": args.mode == "sequential",
		"block_size": args.block_size,
		"silent_mode": args.silent,
		"verbose_mode": args.verbose and not args.silent,
		"fwrite_le": PATHS["fwrite_le_header"]
	}, read_file(PATHS["template"]), args.show_substituted_values))

	# Compile by invoking the shell script
	print("Compiling")

	# Let the system execute aliases by calling os.system
	command = " ".join([CC, CFLAGS, INPUT_FILE, PATHS["fwrite_le"], "-o",
		OUTPUT_FILE, "-I" + PATHS["include_directory"]])
	print(command, flush=True)
	exit(system(command))