#include "cst_metrics.h"

#include "cJSON.h"
#include "cst_agent.h"
#include "os_compat.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

struct cst_metrics {
  FILE *fp;
  char path[OS_PATH_MAX];
};

cst_metrics_t *cst_metrics_open(const char *workspace, const char *session_path) {
  const char *off = getenv("CST_METRICS");
  if (off && strcmp(off, "0") == 0)
    return NULL;
  cst_metrics_t *m = calloc(1, sizeof(*m));
  if (!m)
    return NULL;
  const char *override = getenv("CST_METRICS_PATH");
  if (override && override[0]) {
    snprintf(m->path, sizeof(m->path), "%s", override);
  } else {
    if (!workspace)
      workspace = ".";
    char dir[OS_PATH_MAX], agent[OS_PATH_MAX];
    os_path_join(agent, sizeof(agent), workspace, ".agent");
    os_mkdir(agent, 0755);
    os_path_join(dir, sizeof(dir), agent, "metrics");
    os_mkdir(dir, 0755);
    /* One file per session: the id of the transcript's path (<id>.jsonl, or
     * <id>/session.jsonl in the store's own layout). */
    char leaf[256];
    if (cst_agent_store_id_of_path(session_path, leaf, sizeof(leaf)) != 0)
      snprintf(leaf, sizeof(leaf), "session");
    char file[300];
    snprintf(file, sizeof(file), "%s.jsonl", leaf);
    os_path_join(m->path, sizeof(m->path), dir, file);
  }
  m->fp = fopen(m->path, "ab");
  if (!m->fp) {
    free(m);
    return NULL;
  }
  return m;
}

void cst_metrics_close(cst_metrics_t *m) {
  if (!m)
    return;
  if (m->fp)
    fclose(m->fp);
  free(m);
}

void cst_metrics_emit(cst_metrics_t *m, void *obj) {
  cJSON *o = obj;
  if (!o)
    return;
  if (m && m->fp) {
    if (!cJSON_GetObjectItemCaseSensitive(o, "ts"))
      cJSON_AddNumberToObject(o, "ts", (double)time(NULL));
    char *txt = cJSON_PrintUnformatted(o);
    if (txt) {
      fputs(txt, m->fp);
      fputc('\n', m->fp);
      fflush(m->fp);
      free(txt);
    }
  }
  cJSON_Delete(o);
}

const char *cst_metrics_path(const cst_metrics_t *m) {
  return m ? m->path : NULL;
}