#include "config-ini.h"
#include "types.h"

#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static void free_field(ini_field_t *field) {
	free(field->key);
	free(field->value);
	free(field);
}

static void free_section(ini_section_t *section) {
	ini_field_t *field, *tmp;

	list_for_each_entry_safe(field, tmp, &section->fields, node)
		free_field(field);

	free(section->name);
	free(section);
}

void free_ini_file(ini_file_t *file) {
	ini_section_t *section, *tmp;

	list_for_each_entry_safe(section, tmp, &file->sections, node)
		free_section(section);

	free(file);
}

static bool add_field(ini_section_t *section, const char *key, const char *value) {
	ini_field_t *field = calloc(1, sizeof(*field));
	if (!field)
		return false;

	field->key = strdup(key);
	field->value = strdup(value);

	if (!field->key || !field->value) {
		free_field(field);
		return false;
	}

	list_add_tail(&field->node, &section->fields);

	return true;
}

static ini_section_t * add_section(ini_file_t *file, const char *name) {
	ini_section_t *section = calloc(1, sizeof(*section));
	if (!section)
		return NULL;
	
	section->name = strdup(name);
	if (!section->name) {
		free(section);
		return false;
	}

	INIT_LIST_HEAD(&section->fields);
	list_add_tail(&section->node, &file->sections);

	return section;
}

ini_file_t * read_ini_file(const char *filename) {
	FILE *f = fopen(filename, "r");
	if (!f)
		return NULL;
	
	ini_file_t *file = calloc(1, sizeof(*file));
	if (!file)
		goto error;

	INIT_LIST_HEAD(&file->sections);

	ini_section_t *section = NULL;
	int err = 0;

	char *line = NULL;
	size_t n = 0;

	while (getline(&line, &n, f) >= 0) {
		char *input = line;

		while (isspace(input[0]))
			input++;
		
		if (input[0] == '#' || input[0] == '\0')
			continue;

		size_t len = strlen(input);

		while (isspace(input[len-1]))
			len--;

		if (input[0] == '[') {
			if (input[len-1] != ']') {
				err = EINVAL;
				goto error;
			}

			input[len-1] = '\0';

			section = add_section(file, input+1);
			if (!section)
				goto error;
		} else {
			if (!section) {
				err = EINVAL;
				goto error;
			}

			input[len] = '\0';

			char *delim = strchr(input, '=');
			if (!delim) {
				err = EINVAL;
				goto error;
			}
			
			*delim = '\0';

			if (!add_field(section, input, delim+1))
				goto error;
		}
	}

	if (ferror(f))
		err = EIO;

error:
	free(line);
	fclose(f);

	if (err) {
		free_ini_file(file);
		errno = err;
		return NULL;
	}

	return file;
}