// TODO pretty print json

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stdint.h>
#include <string.h>

#include "json.h"
#include "error.h"

#define JSON_BUF_INITIAL_CAPACITY 1024

static void json_push_context(json_t *buf, json_context_t ctx) {
	if (buf->context_depth >= JSON_MAX_DEPTH) {
		// TODO handle errors better than murdering the program
		error_fatal("Exceeded JSON max nesting depth");
	}
	buf->context_stack[buf->context_depth] = ctx;
	buf->needs_comma[buf->context_depth] = false;
	buf->context_depth++;
}

static void json_pop_context(json_t *buf) {
	if (buf->context_depth <= 0) {
		// TODO better error handling
		error_fatal("JSON context pop");
	}
	buf->context_depth--;
}

bool json_needs_comma(json_t *buf) {
	return buf->needs_comma[buf->context_depth - 1];
}

void json_set_needs_comma(json_t *buf) {
	buf->needs_comma[buf->context_depth - 1] = true;
}

static void json_ensure_capacity(json_t *buf, size_t needed) {
	if (buf->length + needed >= buf->capacity) {
		size_t new_capacity = buf->capacity += JSON_BUF_INITIAL_CAPACITY;
		while (buf->length + needed >= new_capacity) {
			new_capacity += JSON_BUF_INITIAL_CAPACITY;
		}

		char *new_data = realloc(buf->data, new_capacity);
		if (!new_data) {
			error_fatal("realloc: %s", strerror(errno));
		}

		buf->data = new_data;
		buf->capacity = new_capacity;
	}
}

void json_append(json_t *buf, const char *fmt, ...) {
	va_list args;
	va_start(args, fmt);
	int needed = vsnprintf(NULL, 0, fmt, args);
	va_end(args);

	if (needed < 0) {
		error_fatal("vsnprintf: %s", strerror(errno));
	}

	json_ensure_capacity(buf, (size_t)needed + 1);

	va_start(args, fmt);
	vsprintf(buf->data + buf->length, fmt, args);
	va_end(args);

	buf->length += (size_t)needed;
}

void json_init(json_t *buf) {
	buf->capacity = JSON_BUF_INITIAL_CAPACITY;
	buf->length = 0;
	buf->data = malloc(buf->capacity);
	if (!buf->data) {
		error_fatal("malloc: %s", strerror(errno));
	}
	buf->data[0] = '\0';
	buf->context_depth = 0;
	memset(buf->needs_comma, 0, sizeof(buf->needs_comma));
}

void json_free(json_t *buf) {
	if (buf->data) {
		free(buf->data);
	}
	buf->data = NULL;
	buf->length = 0;
	buf->capacity = 0;
	memset(buf->needs_comma, 0, sizeof(buf->needs_comma));
	buf->context_depth = 0;
}

const char *json_get(json_t *buf) {
	return buf && buf->data ? buf->data : "{}";
}

void json_escape_string(json_t *buf, const char *input) {
	json_append(buf, "\"");
	for (size_t i = 0; input[i] != '\0'; i++) {
		char c = input[i];
		switch(c) {
		case '\\':
			json_append(buf, "\\\\");
			break;
		case '"':
			json_append(buf, "\\\"");
			break;
		case '\b':
			json_append(buf, "\\b");
			break;
		case '\f':
			json_append(buf, "\\f");
			break;
		case '\n':
			json_append(buf, "\\n");
			break;
		case '\r':
			json_append(buf, "\\r");
			break;
		case '\t':
			json_append(buf, "\\t");
			break;
		default:
			if ((unsigned char)c < 0x20) {
				json_append(buf, "\\u%04x", c);
			} else {
				json_append(buf, "%c", c);
			}
		}
	}

	json_append(buf, "\"");
}

void json_start_object(json_t *buf) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}

	json_append(buf, "{");
	json_push_context(buf, JSON_CONTEXT_OBJECT);
}

void json_end_object(json_t *buf) {
	json_append(buf, "}");
	json_pop_context(buf);
}

void json_add_string(json_t *buf, const char *key, const char *value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_escape_string(buf, key);
	json_append(buf, ":");
	json_escape_string(buf, value);
	//buf->needs_comma = true;
}

void json_add_string_or_null(json_t *buf, const char *key, const char *value) {
	if (value && value[0] != '\0') {
		json_add_string(buf, key, value);
	} else {
		json_add_null(buf, key);
	}
}

void json_add_int(json_t *buf, const char *key, int value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_escape_string(buf, key);
	json_append(buf, ":%d", value);
}

void json_add_int64(json_t *buf, const char *key, int64_t value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_escape_string(buf, key);
	json_append(buf, ":%lld", value);
}

void json_add_uint64(json_t *buf, const char *key, uint64_t value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_escape_string(buf, key);
	json_append(buf, ":%llu", value);
}

void json_add_double(json_t *buf, const char *key, double value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_escape_string(buf, key);
	json_append(buf, ":%f", value);
}

void json_add_bool(json_t *buf, const char *key, bool value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_escape_string(buf, key);
	json_append(buf, ":%s", value ? "true" : "false");
}

void json_add_null(json_t *buf, const char *key) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_escape_string(buf, key);
	json_append(buf, ":null");
}

void json_start_array(json_t *buf) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}

	json_append(buf, "[");
	json_push_context(buf, JSON_CONTEXT_ARRAY);
}

void json_end_array(json_t *buf) {
	json_append(buf, "]");
	json_pop_context(buf);
}

void json_add_array_start(json_t *buf, const char *key) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}

	json_escape_string(buf, key);
	json_append(buf, ":");
	json_push_context(buf, JSON_CONTEXT_ARRAY);
	json_append(buf, "[");
	buf->needs_comma[buf->context_depth - 1] = false;
}

void json_array_add_string(json_t *buf, const char *value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_escape_string(buf, value);
	json_set_needs_comma(buf);
}

void json_array_add_int(json_t *buf, int value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_append(buf, "%d", value);
}

void json_array_add_int64(json_t *buf, int64_t value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_append(buf, "%lld", value);
}

void json_array_add_uint64(json_t *buf, uint64_t value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_append(buf, "%llu", value);
}

void json_array_add_double(json_t *buf, double value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_append(buf, "%f", value);
}

void json_array_add_bool(json_t *buf, bool value) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_append(buf, "%s", value ? "true" : "false");
}

void json_array_add_null(json_t *buf) {
	if (json_needs_comma(buf)) {
		json_append(buf, ",");
	}
	json_set_needs_comma(buf);

	json_append(buf, "null");
}