#include <errno.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "mailbox.h"
#include "main.h"

/**
 * Parse a line of input into an input struct.
 *
 * @param input_line A line of input.
 * @param res An already allocated input struct to store the result in.
 *
 * @return int -1 if the input is malformed, and 0 otherwise.
 */
static int parse_input_line(char *input_line, struct input *res) {
	// if tmp has anything in it, then we know that extra values have been entered.
	char tmp[2];
	int num_matched = sscanf(input_line, " %d %d %1s", &(res->value), &(res->recipient), tmp);

	return num_matched == 2 ? 0 : -1;
}

/**
 * Convert the given input to an array of input structs.
 *
 * @param num_threads The number of threads that the program has been spawned with.
 * @param res A pointer that will be allocated as an array of inputs. Must be freed by the caller.
 *
 * @return int the number of input lines that were read.
 */
static int get_input(int num_threads, struct input **res) {
	int input_index = 0;
	int current_buffer_size = BUFFER_SIZE;
	char *input_buffer = malloc(current_buffer_size);
	// Keep reaidng until we hit an EOF
	while (true) {
		char *read_result;
		while((read_result = fgets(input_buffer, current_buffer_size, stdin))) {
			int read_size = strlen(input_buffer);
			if (input_buffer[read_size - 1] == '\n') {
				break;
			}

			// Grow our buffer if we nede to read more input.
			current_buffer_size *= 2;
			input_buffer = realloc(input_buffer, current_buffer_size);
		}
		if (read_result == NULL) {
			break;
		}

		struct input current_input;
		int parse_result = parse_input_line(input_buffer, &current_input);
		if (parse_result == -1) {
			// On bad input, we should assume an EOF and stop.
			break;
		} else if (current_input.recipient >= num_threads || current_input.recipient < 0) {
			printf("Invalid recipient id.\n");
			continue;
		}

		*res = realloc(*res, sizeof(struct input));
		memcpy(*res + input_index, &current_input, sizeof(struct input));
		input_index++;
	}

	free(input_buffer);

	return input_index;
}

int main(int argc, char *argv[]) {
	struct input *inputs = NULL;
	if (argc < 2 || argc > 3) {
		printf("%s\n", USAGE_STRING);
		return -1;
	} else if (argc == 3) {
		printf("Not yet implemented.");
		return -1;
	}

	int num_threads = strtol(argv[1], NULL, 10);
	if (errno == ERANGE || (num_threads == 0 && errno == EINVAL)) {
		printf("Invalid number of threads.\n");
	}
	num_threads = num_threads > MAXTHREAD ? MAXTHREAD : num_threads;

	// TODO: Remove this. It's for debugging.
	int num_inputs = get_input(num_threads, &inputs);
	for (int i = 0; i < num_inputs; i++) {
		printf("#%d recipient=%d value=%d\n", i, inputs[i].recipient, inputs[i].value);
	}
	free(inputs);
}