#include <assert.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#include "string.h"
#include "unicode.h"
#include "util.h"

char date[256];

static int parse_section(struct parser *p) {
	str_t *section = str_create();
	uint32_t ch;
	while ((ch = parser_getch(p)) != UTF8_INVALID) {
		if (isdigit(ch)) {
			assert(str_append_ch(section, ch) != -1);
		} else if (ch == ')') {
			if (!section->str) {
				break;
			}
			int sec = strtol(section->str, NULL, 10);
			if (sec < 1 || sec > 9) {
				parser_fatal(p, "Expected section between 1 and 9");
				break;
			}
			str_free(section);
			return sec;
		} else {
			parser_fatal(p, "Expected digit or )");
			break;
		}
	};
	parser_fatal(p, "Expected manual section");
	return -1;
}

static void parse_preamble(struct parser *p) {
	str_t *name = str_create();
	int section = -1;
	uint32_t ch;

	do {
		ch = parser_getch(p);

	while ((ch = parser_getch(p)) != UTF8_INVALID) {

		if (isalnum(ch)) {
			assert(str_append_ch(name, ch) != -1);
		} else if (ch == '(') {
			section = parse_section(p);
		} else if (ch == '\n') {
			if (name->len == 0) {
				parser_fatal(p, "Expected preamble");
			}
			if (section == -1) {
				parser_fatal(p, "Expected manual section");
			}
			char sec[2] = { '0' + section, 0 };
			roff_macro(p, "TH", name->str, sec, date, NULL);
			break;
		}

	} while (ch != UTF8_INVALID);

	}

	str_free(name);
}

static void output_preamble(struct parser *p) {

static void parse_text(struct parser *p) {
	uint32_t ch;
	while ((ch = parser_getch(p)) != UTF8_INVALID) {
		switch (ch) {
		case '\\':
			fprintf(p->output, "\\\\");
			break;
		default:
			utf8_fputch(p->output, ch);
			break;
		}
		if (ch == '\n') {
			break;
		}
	}
}

static void parse_heading(struct parser *p) {
	uint32_t ch;
	int level = 1;
	while ((ch = parser_getch(p)) != UTF8_INVALID) {
		if (ch == '#') {
			++level;
		} else if (ch == ' ') {
			break;
		} else {
			parser_fatal(p, "Invalid start of heading (probably needs a space)");
		}
	}
	switch (level) {
	case 1:
		fprintf(p->output, ".SH ");
		break;
	case 2:
		fprintf(p->output, ".SS ");
		break;
	default:
		parser_fatal(p, "Only headings up to two levels deep are permitted");
		break;
	}
	while ((ch = parser_getch(p)) != UTF8_INVALID) {
		utf8_fputch(p->output, ch);
		if (ch == '\n') {
			break;
		}
	}
}

static void parse_document(struct parser *p) {
	uint32_t ch;
	while ((ch = parser_getch(p)) != UTF8_INVALID) {
		switch (ch) {
		case '#':
			parse_heading(p);
			break;
		case '\n':
			roff_macro(p, "P", NULL);
			break;
		default:
			if (ch == '.') {
				fprintf(p->output, "\\&.");
			} else {
				utf8_fputch(p->output, ch);
			}
			parse_text(p);
			break;
		}
	}
}

static void output_scdoc_preamble(struct parser *p) {

	// TODO: Add version here
	fprintf(p->output, ".\\\" Generated by scdoc\n");
	fprintf(p->output, ".\\\" Fix weird qutation marks:\n");
	fprintf(p->output, ".\\\" http://bugs.debian.org/507673\n");
	fprintf(p->output, ".\\\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html\n");
	fprintf(p->output, ".ie \\n(.g .ds Aq \\(aq\n");
	fprintf(p->output, ".el       .ds Aq '\n");
	fprintf(p->output, ".\\\" Disable hyphenation:\n");
	roff_macro(p, "nh", NULL);
	fprintf(p->output, ".\\\" Generated content:\n");
}

int main(int argc, char **argv) {
	if (argc > 1) {
		fprintf(stderr, "Usage: scdoc < input.scd > output.roff");
		return 1;
	}
	time_t now;
	time(&now);
	struct tm *now_tm = localtime(&now);
	strftime(date, sizeof(date), "%F", now_tm);
	struct parser p = {
		.input = stdin,
		.output = stdout,
		.line = 1,
		.col = 1
	};

	output_preamble(&p);

	output_scdoc_preamble(&p);

	parse_preamble(&p);

	parse_document(&p);

	return 0;
}