#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include "cudl.h"

#define STRIP_WHITESPACE(text) while (isspace(*text)) text++

int cudl_err = CUDL_OK;

static char *fread_all(FILE *file) {
	size_t size;
	char *buffer;
	fseek(file, 0, SEEK_END);
	size = ftell(file);
	rewind(file);
	clearerr(file);
	if ((buffer = malloc(size + 1)) == NULL)
		return NULL;
	if (fread(buffer, 1, size, file) != size) {
		free(buffer);
		return NULL;
	}
	buffer[size] = '\0';
	return buffer;
}

void cudl_debug(struct cudl_value value) {
	int i;
	switch (value.tag) {
		case CUDL_TAG_NULL:
			printf("%%null");
			break;
		case CUDL_TAG_BOOL:
			if (value.data.boolean)
				printf("%%true");
			else
				printf("%%false");
			break;
		case CUDL_TAG_ARRAY:
			printf("[");
			for (i = 0; i < value.data.array.length; i++)
				cudl_debug(value.data.array.values[i]);
			printf("]");
			break;
		default:
			printf("UNKNOWN");
			break;
	}
}

/* Free all children of the value, not the value itself */
void cudl_deinit_value(struct cudl_value value) {
	int i;
	switch (value.tag) {
		case CUDL_TAG_ARRAY:
			for (i = 0; i < value.data.array.length; i++) {
				cudl_deinit_value(value.data.array.values[i]);
			}
			free(value.data.array.values);
			break;
		case CUDL_TAG_NULL:
		case default:
			break;
	}
}

/* Parse a value from input and store it in value.
 * Return the number of bytes consumed.
 * Input must end with a null byte */
size_t parse_value(char *input, struct cudl_value *value);

static size_t parse_bool_or_null(char *input, struct cudl_value *value) {
	if (strncmp(input, "null", 4)) {
		value->tag = CUDL_TAG_NULL;
		return 4;
	}
	if (strncmp(input, "true", 4)) {
		value->tag = CUDL_TAG_BOOL;
		value->data.boolean = 1;
		return 4;
	}
	if (strncmp(input, "false", 5)) {
		value->tag = CUDL_TAG_BOOL;
		value->data.boolean = 0;
		return 5;
	}
	cudl_err = CUDL_ERR_EXPECTED_BOOL_OR_NULL;
	return 0;
}

static size_t parse_array(char *input, struct cudl_value *value) {
	size_t length, capacity;
	struct cudl_value *values, *newvalues;
	int i;
	char *original_input;

	original_input = input;
	value->tag = CUDL_TAG_ARRAY;
	length = 0;
	capacity = 8;
	if ((values = malloc(capacity * sizeof(struct cudl_value))) == NULL) {
		cudl_err = CUDL_ERR_OUT_OF_MEMORY;
		return 0;
	}

	STRIP_WHITESPACE(input);
	for (;;) {
		if (*input == '\0') {
			cudl_err = CUDL_ERR_UNMATCHED_BRACK;
			for (i = 0; i < length; i++)
				cudl_deinit_value(values[i]);
			free(values);
			return 0;
		} else if (*input == ']') {
			input++;
			values = realloc(values, length * sizeof(struct cudl_value));
			value->data.array.length = length;
			value->data.array.values = values;
			return input - original_input;
		}
		if (length >= capacity) {
			if ((newvalues = realloc(values, 2 * capacity * sizeof(struct cudl_value))) == NULL) {
				cudl_err = CUDL_ERR_OUT_OF_MEMORY;
				for (i = 0; i < length; i++)
					cudl_deinit_value(values[i]);
				free(values);
				return 0;
			}
			capacity *= 2;
		}
		input += parse_value(input, values + length);
		if (cudl_err) {
			for (i = 0; i < length; i++) {
				cudl_deinit_value(values[i]);
			}
			free(values);
			return 0;
		}
		length++;
	}
}

static size_t _parse_value(char *input, struct cudl_value *value) {
	if (*input == '%')
		return parse_bool_or_null(++input, value) + 1;
	if (*input == '[')
		return parse_array(++input, value) + 1;
	cudl_err = CUDL_ERR_UNRECOGNISED_VALUE;
	return 0;
}

static size_t parse_value(char *input, struct cudl_value *value) {
	char *original_input;
	original_input = input;
	input += _parse_value(input, value);
	STRIP_WHITESPACE(input);
	return input - original_input;
}

void cudl_parse_from_file(FILE *file, struct cudl_value *value) {
	char *input;
	if ((input = fread_all(file)) == NULL) {
		if (ferror(file))
			cudl_err = CUDL_ERR_READING;
		else
			cudl_err = CUDL_ERR_OUT_OF_MEMORY;
		return;
	}
	input += cudl_parse(input, value);
	if (*input != '\0')
		cudl_deinit_value(*value);
	free(input);
}

size_t cudl_parse(char *input, struct cudl_value *value) {
	STRIP_WHITESPACE(input);
	return parse_value(input, value);
}