// main.c - Moving average calculator using ts library
// Computes a simple moving average over configurable period and displays results.

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

#define TS_IMPLEMENTATION
#include "ts.h"

#define BUFFER_SIZE 100
#define DISPLAY_N 20

static void usage(const char *prog)
{
    fprintf(stderr, "Usage: %s [period]\n", prog);
    fprintf(stderr, "  period: moving average window (1-%d, default: 10)\n", BUFFER_SIZE);
}

int main(int argc, char *argv[]) {
    uint_t period = 10;
    if (argc > 1 && (strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0)) {
        usage(argv[0]);
        return 0;
    }
    if (argc > 1) {
        char *endptr = NULL;
        errno = 0;
        long val = strtol(argv[1], &endptr, 10);
        if (endptr == argv[1] || *endptr != '\0' || errno == ERANGE) {
            fprintf(stderr, "Error: invalid period '%s'\n", argv[1]);
            usage(argv[0]);
            return 1;
        }
        if (val < 1 || val > BUFFER_SIZE) {
            fprintf(stderr, "Error: period must be between 1 and %d\n", BUFFER_SIZE);
            usage(argv[0]);
            return 1;
        }
        period = (uint_t)val;
    }
    if (period == 0 || period > BUFFER_SIZE) {
        fprintf(stderr, "Error: period must be between 1 and %d\n", BUFFER_SIZE);
        usage(argv[0]);
        return 1;
    }

    fp_t input[BUFFER_SIZE];
    fp_t output[BUFFER_SIZE];
    for (int_t i = 0; i < (int_t)BUFFER_SIZE; i++) {
        output[i] = 0;
    }

    if (!ts_fill(input, BUFFER_SIZE, 0, (fp_t)BUFFER_SIZE)) {
        fprintf(stderr, "ts_fill failed\n");
        return 1;
    }

    fp_t * const y[1] = { output };
    fp_t const * const x[1] = { input };

    ts_constant_t c;
    memset(&c, 0, sizeof(c));
    *(uint_t *)c.data = period;
    int ret = ts_average(y, 1, x, 1, BUFFER_SIZE, &c);
    if (ret == -1) {
        fprintf(stderr, "ts_average failed\n");
        return 1;
    }

    /* Validate output: first valid value is at index period-1 */
    uint_t offset = period - 1;
    if (offset >= BUFFER_SIZE) {
        fprintf(stderr, "error: period exceeds buffer size\n");
        return 1;
    }

    /* Clamp display range to valid output */
    uint_t display_end = DISPLAY_N < BUFFER_SIZE ? DISPLAY_N : BUFFER_SIZE;
    if (offset >= display_end) {
        fprintf(stderr, "warning: period (%" TS_PRIuint ") >= display count (%" TS_PRIuint "), showing available data\n", period, display_end);
        display_end = BUFFER_SIZE;
    }

    for (uint_t i = offset; i < display_end; i++) {
        printf("input[%" TS_PRIuint "] = %f  SMA[%" TS_PRIuint "] = %f\n", i, input[i], i, output[i]);
    }

    return 0;
}