#pragma once
#include <stddef.h>
#include "fieldstat.h" // for fieldstat_tag

#ifdef __cplusplus
extern "C"
{
#endif

struct fieldstat_easy;

/* 
 * new a fieldstat_easy instance.
    * @param max_thread_num: max thread number of this instance.
    * @param name: name of this instance. Will appear in output json. Can be NULL.
    * @param tags: tags of this instance. Will appear in output json. Can be NULL.
*/
struct fieldstat_easy *fieldstat_easy_new(int max_thread_num, const char *name, const struct fieldstat_tag *tags, size_t n_tag);
/*
    * free a fieldstat_easy instance.
*/
void fieldstat_easy_free(struct fieldstat_easy *fse);
/*
    * enable auto output. both data of accumulated and delta will be output.
    * @param output_path: output file path. Should be identical to the one in python config.
    * @param interval_second: output interval in second.
    * @return: 0 if success, -1 if failed to open file. -2 if the output is already enabled.
*/
int fieldstat_easy_enable_auto_output(struct fieldstat_easy *pthis, const char *output_path, int interval_second);

/*
    affect the output of fieldstat_easy_output and fieldstat_easy_output_array.
    let json exporter output delta value by the side of the original value(accumulated). If a cell / metric is new, the delta value is the same as the original value.
    Outputting delta value is disabled by default.
    When the fieldstat instance is reset, the delta value will be reset. (next output will be the original value)
    Only affects the metrics of counter type.
    Outputting delta value is time-consuming. Be cautious when enabling it.
*/
void fieldstat_easy_enable_delta_in_active_output(struct fieldstat_easy *fse);

/*
    * @brief add a metric to the cube of cube_id. One metric may be associated with different cells.
    * @param metric_name: name of the metric. Cannot be NULL. Must be unique.
    * @return metric id>=0 if success. If failed, return FS_ERR_NULL_HANDLER, FS_ERR_INVALID_KEY(when metric_name is not unique in this cube).
    * For the error code, see fieldstat.h
*/
int fieldstat_easy_register_counter(struct fieldstat_easy *fse, const char *name);
/*
    * @brief refer to fieldstat_easy_register_counter.
    * @param lowest_trackable_value: the lowest value that can be tracked (distinguishable from 0) by the histogram. Must be >= 1.
    * @param highest_trackable_value: the highest value to be tracked by the histogram. Must be >= 2 * lowest_trackable_value.
    * @param significant_figures: the precision of the histogram. Must be in [1, 5].
    * @return metric id if success. If failed, return FS_ERR_NULL_HANDLER, FS_ERR_INVALID_KEY(when metric_name is not unique in this cube), or FS_ERR_INVALID_PARAM(if any of the 3 params are out of range)
    * For the error code, see fieldstat.h
*/
int fieldstat_easy_register_histogram(struct fieldstat_easy *fse, const char *name, long long lowest_trackable_value, long long highest_trackable_value, int significant_figures);
/*
    * Output the accumulated data to a json string.
    * @param buff: output buffer. User should free it after use.
*/
void fieldstat_easy_output(struct fieldstat_easy *fse, char **buff, size_t *buff_len);
void fieldstat_easy_output_array(struct fieldstat_easy *fse, char ***json_objects, size_t *n_object);
/*
    Call fieldstat_easy_output_array and then reset the instance. 
    Will fail and return -1 if fieldstat_easy_enable_auto_output is called, since the behavior is hard to define. Return 0 if success.
    The thread will be blocked until output is finished.
*/
int fieldstat_easy_output_array_and_reset(struct fieldstat_easy *fse, char ***json_objects, size_t *n_object);
/*
    * @brief let the value of counter metric of tags increase by `increment`.
    * @param thread_id: thread id. Must be in [0, max_thread_num).
    * @param metric_id: metric id, previously returned by fieldstat_easy_register_counter.
    * @param increment: increment of the counter metric. Can be negative.
    * return -1 also when the thread_id is out of range.FS_ERR_INVALID_METRIC_ID metric_id is not registered.
*/
int fieldstat_easy_counter_incrby(struct fieldstat_easy *fse, int thread_id, int metric_id, const struct fieldstat_tag *tags, size_t n_tag, long long increment);
/*
    * @brief let the value of counter metric of tags equal to `value`.
    *    for other notes, see fieldstat_easy_counter_incrby.
    * The value will be output by summing each ones in different threads, exactly the same as values set by fieldstat_easy_counter_incrby.
*/
int fieldstat_easy_counter_set(struct fieldstat_easy *fse, int thread_id, int metric_id, const struct fieldstat_tag *tags, size_t n_tag, long long value);
/* 
    * @brief Add a value to the histogram metric of cell_id. Histogram will record the distribution of the values.
             The value bigger than highest_trackable_value will be set to highest_trackable_value. The value less than lowest_trackable_value will be tried to record, and, if succeed, remains in the record as -inf(most of the time) or 0(if value == 0)
    * @param value: value of the histogram metric.
    * @return FS_OK if success. FS_ERR_NULL_HANDLER, FS_ERR_INVALID_CUBE_ID, FS_ERR_INVALID_METRIC_ID if fail.
    * return -1 also when the thread_id is out of range.
*/
int fieldstat_easy_histogram_record(struct fieldstat_easy *fse, int thread_id, int metric_id, const struct fieldstat_tag *tags, size_t n_tag, long long value);

#ifdef __cplusplus
}
#endif