#include "vm/vm.h"
#include "vm/print.h"
#include "parse/parse.h"
#include "parse/lex.h"
#include "io.h"
#include "bitset.h"
#include "bytecode.h"

#include <stdio.h>
#include <string.h>

static int do_print_bytecode = 0;
static int do_print_tokens = 0;
static int do_step = 0;
static int do_serialize_bytecode = 0;
static char *input_filename = "-";

static int serialize_bytecode(FILE *outf, l2_word *data, size_t len) {
	char header[4] = { 0x1b, 0x6c, 0x32, 0x63 };
	if (fwrite(header, 1, 4, outf) < 4) {
		fprintf(stderr, "Write error\n");
		return -1;
	}

	char version[4] = {
		(l2_bytecode_version & 0xff000000ul) >> 24,
		(l2_bytecode_version & 0x00ff0000ul) >> 16,
		(l2_bytecode_version & 0x0000ff00ul) >> 8,
		(l2_bytecode_version & 0x000000fful) >> 0,
	};
	if (fwrite(version, 1, 4, outf) < 4) {
		fprintf(stderr, "Write error\n");
		return -1;
	}

	for (size_t i = 0; i < len; ++i) {
		l2_word word = data[i];
		char *dest = (char *)&data[i];
		dest[0] = (word & 0xff000000ul) >> 24;
		dest[1] = (word & 0x00ff0000ul) >> 16;
		dest[2] = (word & 0x0000ff00ul) >> 8;
		dest[3] = (word & 0x000000fful) >> 0;
	}

	if (fwrite(data, 4, len, outf) < len) {
		fprintf(stderr, "Write error\n");
		return -1;
	}

	return 0;
}

static int load_bytecode(FILE *inf, struct l2_io_writer *w) {
	// Header is already read by main

	char version_buf[4];
	if (fread(version_buf, 1, 4, inf) < 4) {
		fprintf(stderr, "Read error\n");
		return -1;
	}

	int version = 0 |
		((unsigned int)version_buf[0]) << 24 |
		((unsigned int)version_buf[1]) << 16 |
		((unsigned int)version_buf[2]) << 8 |
		((unsigned int)version_buf[3]) << 0;
	if (version != l2_bytecode_version) {
		fprintf(
				stderr, "Version mismatch! Bytecode file uses bytecode version %i"
				", but your build of lang2 uses bytecode version %i\n",
				version, l2_bytecode_version);
		return -1;
	}

	struct l2_bufio_writer writer;
	l2_bufio_writer_init(&writer, w);

	char buffer[4096];

	while (1) {
		size_t n = fread(buffer, 1, sizeof(buffer), inf);
		if (n < 4) {
			l2_bufio_flush(&writer);
			return 0;
		}

		for (size_t i = 0; i < n; i += 4) {
			l2_word word = 0 |
				((unsigned int)buffer[i + 0]) << 24 |
				((unsigned int)buffer[i + 1]) << 16 |
				((unsigned int)buffer[i + 2]) << 8 |
				((unsigned int)buffer[i + 3]) << 0;
			l2_bufio_put_n(&writer, &word, 4);
		}

	}
}

static int parse_text(FILE *inf, struct l2_io_writer *w) {
	// Init lexer with its input reader
	struct l2_io_file_reader r;
	r.r.read = l2_io_file_read;
	r.f = inf;
	struct l2_lexer lexer;
	l2_lexer_init(&lexer, &r.r);
	if (do_print_tokens) {
		lexer.do_log_tokens = 1;
	}

	// Init gen with its output writer
	struct l2_generator gen;
	l2_gen_init(&gen, w);

	struct l2_parse_error err;
	if (l2_parse_program(&lexer, &gen, &err) < 0) {
		fprintf(stderr, "Parse error: %s:%i:%i: %s\n",
				input_filename, err.line, err.ch, err.message);
		l2_gen_free(&gen);
		fclose(inf);
		return -1;
	}

	l2_gen_free(&gen);
	return 0;
}

static void step_through(struct l2_vm *vm) {
	printf("=====\n\nInitial state:\n");
	l2_vm_print_state(vm);

	char buf[16];
	while (!vm->halted) {
		size_t iptr = vm->iptr;
		printf("\n======\n\n(%d) Will run instr: ", vm->iptr);
		l2_vm_print_op(vm->ops, vm->opcount, &iptr);
		if (fgets(buf, sizeof(buf), stdin) == NULL) {
			break;
		}

		l2_vm_step(vm);
		l2_vm_print_state(vm);
	}
}

static void usage(const char *argv0) {
	printf("Usage: %s [options] [input|-]\n", argv0);
	printf("\n");
	printf("Options:\n");
	printf("  --help:            Print this help text\n");
	printf("  --bytecode:        Print the generated bytecode, don't execute\n");
	printf("  --tokens:          Print the tokens as the program is parsed, don't execute\n");
	printf("  --step:            Step through the program\n");
	printf("  --output,-o <out>: Write bytecode to file\n");
}

int main(int argc, char **argv) {
	int was_inf_set = 0;
	FILE *inf = stdin;
	FILE *outbc = NULL;

	int dashes = 0;
	for (int i = 1; i < argc; ++i) {
		if (!dashes && strcmp(argv[i], "--help") == 0) {
			usage(argv[0]);
			return 0;
		} else if (!dashes && strcmp(argv[i], "--bytecode") == 0) {
			do_print_bytecode = 1;
		} else if (!dashes && strcmp(argv[i], "--tokens") == 0) {
			do_print_tokens = 1;
		} else if (!dashes && strcmp(argv[i], "--step") == 0) {
			do_step = 1;
		} else if (!dashes && (
				strcmp(argv[i], "--output") == 0 || strcmp(argv[i], "-o") == 0)) {
			if (i == argc - 1) {
				fprintf(stderr, "%s expects an argument\n", argv[i]);
				return 1;
			}

			do_serialize_bytecode = 1;
			i += 1;
			if (strcmp(argv[i], "-") == 0) {
				outbc = stdout;
			} else {
				outbc = fopen(argv[i], "w");
				if (outbc == NULL) {
					perror(argv[i]);
					return 1;
				}
			}
		} else if (strcmp(argv[i], "--") == 0) {
			dashes = 1;
		} else if (strcmp(argv[i], "-") == 0) {
			input_filename = "-";
			inf = stdin;
		} else if (!was_inf_set) {
			input_filename = argv[i];
			inf = fopen(argv[i], "r");
			was_inf_set = 1;
			if (inf == NULL) {
				perror(argv[i]);
				return 1;
			}
		} else {
			printf("Unexpected argument: %s\n", argv[i]);
			usage(argv[0]);
			return 1;
		}
	}

	struct l2_io_mem_writer bytecode_writer = {0};
	bytecode_writer.w.write = l2_io_mem_write;

	// 
	int headerbyte = fgetc(inf);
	if (headerbyte == EOF || ungetc(headerbyte, inf) == EOF) {
		fprintf(stderr, "%s: Reading file failed.\n", input_filename);
		return 1;
	}

	// Detect whether input is compiled bytecode or not
	// (compile bytecode starts with (ESC) 'l' '2' 'c')
	unsigned char header[4];
	if (
			headerbyte == 0x1b &&
			fread(header, 1, 4, inf) >= 4 &&
			header[0] == 0x1b && header[1] == 0x6c &&
			header[2] == 0x32 && header[3] == 0x63) {
		if (load_bytecode(inf, &bytecode_writer.w) < 0) {
			return 1;
		}
	} else if (headerbyte == 0x1b) {
		fprintf(
				stderr, "%s: Corrupt file? Start byte is 0x1b (ESC)"
				"but the header is wrong\n",
				input_filename);
		return 1;
	} else {
		if (parse_text(inf, &bytecode_writer.w) < 0) {
			return 1;
		}
	}
	fclose(inf);

	if (do_print_bytecode) {
		l2_vm_print_bytecode(bytecode_writer.mem, bytecode_writer.len / sizeof(l2_word));
	}

	if (do_serialize_bytecode) {
		serialize_bytecode(outbc, bytecode_writer.mem, bytecode_writer.len / sizeof(l2_word));
	}

	if (do_print_bytecode || do_print_tokens || do_serialize_bytecode) {
		free(bytecode_writer.mem);
		return 0;
	}

	struct l2_vm vm;
	l2_vm_init(&vm, bytecode_writer.mem, bytecode_writer.len / sizeof(l2_word));

	if (do_step) {
		step_through(&vm);
	} else {
		l2_vm_run(&vm);
	}

	l2_vm_free(&vm);
	free(bytecode_writer.mem);
}