#include "trace.h"

#include <assert.h>
#include <malloc.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <sqlite3.h>

enum {
	k_buffer_size = 4 * 1024 * 1024,
};

typedef struct _tf_trace_t
{
	char buffer[k_buffer_size];
	int write_offset;
} tf_trace_t;

tf_trace_t* tf_trace_create()
{
	tf_trace_t* trace = malloc(sizeof(tf_trace_t));
	memset(trace, 0, sizeof(*trace));
	return trace;
}

void tf_trace_destroy(tf_trace_t* trace)
{
	free(trace);
}

static int64_t _trace_ts()
{
	int64_t result = 0;
	struct timespec ts;
	if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0) {
		result = (ts.tv_sec * 1e9 + ts.tv_nsec) / 1e3;
	}
	return result;
}

static void _trace_append(tf_trace_t* trace, const char* buffer, size_t size)
{
	if (trace->write_offset + size >= k_buffer_size) {
		trace->buffer[trace->write_offset] = '\0';
		trace->write_offset = 0;
	}

	if (trace->write_offset + size < k_buffer_size) {
		memcpy(trace->buffer + trace->write_offset, buffer, size);
		trace->write_offset += size;
		trace->buffer[trace->write_offset++] = '\n';
	}
}

void tf_trace_counter(tf_trace_t* trace, const char* name, int argc, const char** arg_names, const int64_t* arg_values)
{
	if (!trace) {
		return;
	}

	char line[1024];
	int p = 0;
	p += snprintf(line + p, sizeof(line) - p, "{\"ph\": \"C\", \"pid\": %d, \"ts\": %" PRId64 ", \"name\": \"%s\", \"args\": {", getpid(), _trace_ts(), name);
	for (int i = 0; i < argc; i++)
	{
		p += snprintf(line + p, sizeof(line) - p, "\"%s\": %" PRId64 "%s", arg_names[i], arg_values[i], i == argc - 1 ? "}}," : ", ");
	}

	_trace_append(trace, line, p);
}

void tf_trace_begin(tf_trace_t* trace, const char* name)
{
	if (!trace) {
		return;
	}

	char line[1024];
	int p = snprintf(line, sizeof(line), "{\"ph\": \"B\", \"pid\": %d, \"ts\": %" PRId64 ", \"name\": \"", getpid(), _trace_ts());
	for (const char* c = name; *c && p < (int)sizeof(line); c++) {
		switch (*c) {
		case '"':
		case '\\':
			line[p++] = '\\';
			if (p < (int)sizeof(line)) {
				line[p++] = *c;
			}
			break;
		default:
			line[p++] = *c;
			break;
		}
	}
	p += snprintf(line + p, sizeof(line) - p, "\"},");
	_trace_append(trace, line, p);
}

void tf_trace_end(tf_trace_t* trace)
{
	if (!trace) {
		return;
	}

	char line[1024];
	int p = snprintf(line, sizeof(line), "{\"ph\": \"E\", \"pid\": %d, \"ts\": %" PRId64 "},", getpid(), _trace_ts());
	_trace_append(trace, line, p);
}

char* tf_trace_export(tf_trace_t* trace)
{
	if (!trace) {
		return NULL;
	}

	static const int k_extra_size = 1024;
	char* buffer = malloc(k_buffer_size + k_extra_size);
	const char* newline = strchr(trace->buffer + trace->write_offset, '\n');
	int begin = newline ? newline - trace->buffer : 0;
	size_t size = 0;
	size += snprintf(buffer, k_buffer_size, "{\"displayTimeUnit\": \"ns\",\n\"traceEvents\": [\n");
	if (begin) {
		size_t this_size = strlen(trace->buffer + begin);
		memcpy(buffer + size, trace->buffer + begin, this_size);
		size += this_size;
	}
	memcpy(buffer + size, trace->buffer, trace->write_offset);
	size += trace->write_offset;
	if (size > 2 && buffer[size - 1] == '\n' && buffer[size - 2] == ',') {
		buffer[size - 2] = '\n';
		size--;
	}
	size += snprintf(buffer + size, k_buffer_size - size, "]}\n");
	buffer[size] = '\0';
	assert(size < (size_t)k_buffer_size + k_extra_size);
	return buffer;
}

static int _tf_trace_sqlite_callback(unsigned int t, void* c, void* p, void* x)
{
	tf_trace_t* trace = c;
	switch (t) {
	case SQLITE_TRACE_STMT:
		{
			const char* statement = x;
			if (statement[0] != '-' || statement[1] != '-') {
				tf_trace_begin(trace, statement);
			}
		}
		break;
	case SQLITE_TRACE_PROFILE:
		tf_trace_end(trace);
		break;
	}
	return 0;
}

void tf_trace_sqlite(tf_trace_t* trace, sqlite3* sqlite)
{
	if (sqlite) {
		sqlite3_trace_v2(sqlite, SQLITE_TRACE_STMT | SQLITE_TRACE_PROFILE, _tf_trace_sqlite_callback, trace);
	} else {
		sqlite3_trace_v2(sqlite, 0, NULL, NULL);
	}
}