#!/bin/sh
set -eu

[ "$#" -eq 2 ] || [ "$#" -eq 3 ] || {
    echo "usage: $0 BASELINE_JSON CANDIDATE_JSON [OUTPUT_JSON]" >&2
    exit 2
}
baseline=$1
candidate=$2
output=${3:-}

analyze() {
    jq -n --slurpfile baseline "$baseline" --slurpfile candidate "$candidate" '
      $baseline[0] as $b | $candidate[0] as $c |
      if ($b.schema_version != 1 or $c.schema_version != 1 or
          $b.kernel != $c.kernel or $b.hardware != $c.hardware or
          $b.input_size != $c.input_size or $b.output_size != $c.output_size or
          $b.iterations != $c.iterations or
          $b.warmup != $c.warmup or
          ($b.samples_gbps | length) < 3 or ($c.samples_gbps | length) < 3)
      then error("kernel benchmark inputs are not comparable") else
        (["buffer_mode", "command_span", "matrix_slots"] |
          map(select($b[.] != $c[.]))) as $axes |
        if ($axes | length) != 1 then error("exactly one tuning axis must change") else
        (100 * ($c.mean_gbps / $b.mean_gbps - 1)) as $delta |
        (100 * $b.stddev_gbps / $b.mean_gbps) as $bcv |
        (100 * $c.stddev_gbps / $c.mean_gbps) as $ccv |
        ([ $bcv, $ccv ] | max) as $noise |
        {
          schema_version: 1,
          axis: {name: $axes[0], baseline: $b[$axes[0]], candidate: $c[$axes[0]]},
          metric: {
            baseline_gbps: $b.mean_gbps,
            candidate_gbps: $c.mean_gbps,
            delta_pct: $delta,
            baseline_cv_pct: $bcv,
            candidate_cv_pct: $ccv,
            observed_noise_floor_pct: $noise
          },
          promotion: {
            threshold_passed: ($delta >= 3 and $delta > $noise),
            eligible: false,
            reason: "microbenchmark only; authentic full-model correctness and performance gates are required"
          }
        } end
      end'
}

if [ -n "$output" ]; then analyze > "$output"; else analyze; fi