#!/usr/bin/env bash
# Part of JoeyLib, Copyright (c) 2026 Scott Duensing, under the MIT License.
# See LICENSE.md for license information.
# SPDX-License-Identifier: MIT
#
# check-sfxmix.sh - Host-cc differential harness for the shared SFX
# overlay mixer (src/core/audioSfxMix.c), built on the check-blank.sh /
# check-millis.sh pattern. Compiles the CURRENT mixer TU with the host
# cc plus tests/host/sfxMixHost.c and runs a fixed-seed scenario set
# (fixed-buffer + streaming slots, rate up/down, multi-slot, mid-mix
# refill and end-of-stream, amplitude 0/max, >64k read positions).
#
# First run captures tests/goldens/sfxmix-baseline.txt (capture it
# against the CURRENT mixer (the go-forward reference)); later runs diff per scenario:
#   default             exact mode: FNV-1a hash + raw bytes must match
#                       the baseline (gate for findings #7 and #33,
#                       which must be bit-identical).
#   JL_SFX_TOLERANCE=1  per-sample mode for finding #6: prints each
#                       scenario's max-abs-delta and allows a deviation
#                       of tolerance * slots per output sample (the
#                       1-LSB interp deviation stacks across
#                       simultaneous slots before the clamp).
#
# The harness binary is also run twice and the outputs compared, so a
# nondeterministic harness (or mixer reading uninitialized memory)
# fails loudly instead of producing a flaky baseline.
set -euo pipefail

repo=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
cc=${CC:-cc}
work=$(mktemp -d -t joeylib-sfxmix.XXXXXX)
trap 'rm -rf "$work"' EXIT
baseline="$repo/tests/goldens/sfxmix-baseline.txt"

cd "$repo"
# BLANK platform: audioSfxMix.c is portable C with no jlp* hooks; the
# stream fill callback is mocked inside sfxMixHost.c.
"$cc" -DJOEYLIB_PLATFORM_BLANK \
    -Iinclude -Iinclude/joey -Isrc/core -Wall \
    src/core/audioSfxMix.c tests/host/sfxMixHost.c \
    -o "$work/sfxMixHost"

"$work/sfxMixHost" > "$work/out1.txt"
"$work/sfxMixHost" > "$work/out2.txt"
if ! cmp -s "$work/out1.txt" "$work/out2.txt"; then
    echo "check-sfxmix: FAIL - harness output differs across two runs (nondeterministic)" >&2
    exit 1
fi

if [ ! -f "$baseline" ]; then
    mkdir -p "$(dirname "$baseline")"
    cp "$work/out1.txt" "$baseline"
    count=$(grep -c '^name=' "$baseline")
    echo "check-sfxmix: baseline captured ($count scenarios) -> tests/goldens/sfxmix-baseline.txt"
    exit 0
fi

tolerance="${JL_SFX_TOLERANCE:-}"
if [ -n "$tolerance" ]; then
    echo "check-sfxmix: comparing against baseline (per-sample, tolerance ${tolerance} LSB * slots)"
else
    echo "check-sfxmix: comparing against baseline (exact hash mode)"
fi

if awk -v tolerance="$tolerance" '
    BEGIN {
        for (i = 0; i < 256; i++) {
            byteOf[sprintf("%02X", i)] = i
        }
    }
    FNR == 1 {
        name = ""
    }
    {
        gsub(/^[ \t\r]+|[ \t\r]+$/, "")
    }
    /^name=/ {
        delete fields
        for (i = 1; i <= NF; i++) {
            at = index($i, "=")
            fields[substr($i, 1, at - 1)] = substr($i, at + 1)
        }
        name = fields["name"]
        order[ARGIND, ++count[ARGIND]] = name
        hash[ARGIND, name]  = fields["hash"]
        slots[ARGIND, name] = fields["slots"] + 0
        raw[ARGIND, name]   = ""
        seen[ARGIND, name]  = 1
    }
    /^raw=/ && name != "" {
        raw[ARGIND, name] = toupper(substr($0, 5))
    }
    END {
        same = count[1] == count[2]
        for (i = 1; i <= count[1] && same; i++) {
            same = order[1, i] == order[2, i]
        }
        if (!same) {
            print "check-sfxmix: scenario list changed vs baseline"
            line = "  baseline:"
            for (i = 1; i <= count[1]; i++) {
                line = line " " order[1, i]
            }
            print (count[1] > 0 ? line : line " ")
            line = "  current: "
            for (i = 1; i <= count[2]; i++) {
                line = line " " order[2, i]
            }
            print (count[2] > 0 ? line : line " ")
            failed = 1
        }
        for (i = 1; i <= count[1]; i++) {
            name = order[1, i]
            if (!((2, name) in seen)) {
                continue
            }
            label = sprintf("  %-24s", name ":")
            baseLen = length(raw[1, name]) / 2
            curLen  = length(raw[2, name]) / 2
            if (baseLen != curLen) {
                printf "%s FAIL (length %d -> %d)\n", label, baseLen, curLen
                failed = 1
                continue
            }
            if (tolerance == "") {
                if (hash[1, name] == hash[2, name] && raw[1, name] == raw[2, name]) {
                    printf "%s PASS (hash %s)\n", label, hash[2, name]
                } else {
                    printf "%s FAIL (hash %s -> %s)\n", label, hash[1, name], hash[2, name]
                    failed = 1
                }
                continue
            }
            maxDelta = 0
            for (b = 1; b <= baseLen; b++) {
                delta = byteOf[substr(raw[1, name], 2 * b - 1, 2)] - byteOf[substr(raw[2, name], 2 * b - 1, 2)]
                delta = delta < 0 ? -delta : delta
                maxDelta = delta > maxDelta ? delta : maxDelta
            }
            allowed = tolerance * slots[1, name]
            printf "%s maxAbsDelta=%d (allowed %d) %s\n", label, maxDelta, allowed, (maxDelta <= allowed ? "PASS" : "FAIL")
            failed = failed || maxDelta > allowed
        }
        exit failed ? 1 : 0
    }' "$baseline" "$work/out1.txt"
then
    echo "check-sfxmix: PASS"
else
    echo "check-sfxmix: FAIL (mixer output diverged from tests/goldens/sfxmix-baseline.txt)" >&2
    exit 1
fi