#!/usr/bin/env bash
# SPDX-License-Identifier: MIT
# Copyright (C) Intel Corporation
#
# Prepare the sample video for the scene-change-detection use case.
# This use case uses classical computer vision (frame histogram
# comparison) with OpenCV; no model export or quantization is required.
#
# A single continuous shot never triggers a scene change, so this script
# builds a short montage (test_video.mp4) from several distinct sample
# clips joined with hard cuts. Each clip is normalized to the same size and
# frame rate and trimmed to 2 seconds, producing a scene change every 2
# seconds that the histogram detector flags.
# Usage: ./export_and_quantize.sh

set -euo pipefail

SAMPLE_BASE_URL="https://github.com/intel-iot-devkit/sample-videos/raw/master"
# Distinct scenes joined into the montage, in order.
SAMPLE_CLIPS=(
    "one-by-one-person-detection.mp4"
    "bottle-detection.mp4"
    "person-bicycle-car-detection.mp4"
    "head-pose-face-detection-female.mp4"
)
CLIP_SECONDS=2      # length of each scene in the montage
CLIP_WIDTH=640
CLIP_HEIGHT=360
CLIP_FPS=30

# Ask for approval before downloading models and sample files
echo ""
echo "This script will download:"
echo "  - Model weights and/or sample files"
echo ""
read -p "Continue with downloads? (yes/no): " APPROVAL
if [[ "${APPROVAL}" != "yes" ]]; then
    echo "Download cancelled by user."
    exit 0
fi

command -v ffmpeg >/dev/null 2>&1 || {
    echo "ERROR: ffmpeg is required to build the montage sample video." >&2
    exit 1
}

echo ""
if [[ -f test_video.mp4 ]]; then
    echo "Already present: test_video.mp4"
else
    echo "--- Downloading sample clips and building montage ---"
    WORK_DIR="$(mktemp -d)"
    trap 'rm -rf "${WORK_DIR}"' EXIT
    CONCAT_LIST="${WORK_DIR}/concat.txt"
    : > "${CONCAT_LIST}"

    idx=0
    for clip in "${SAMPLE_CLIPS[@]}"; do
        src="${WORK_DIR}/src_${idx}.mp4"
        norm="${WORK_DIR}/clip_${idx}.mp4"
        echo "Downloading: ${clip}"
        wget -q -O "${src}" "${SAMPLE_BASE_URL}/${clip}"
        # Trim to CLIP_SECONDS and normalize size/fps so the clips concatenate
        # cleanly and every join is a clean scene cut.
        ffmpeg -nostdin -y -loglevel error -t "${CLIP_SECONDS}" -i "${src}" \
            -vf "scale=${CLIP_WIDTH}:${CLIP_HEIGHT},fps=${CLIP_FPS},setsar=1" \
            -an -pix_fmt yuv420p "${norm}"
        echo "file 'clip_${idx}.mp4'" >> "${CONCAT_LIST}"
        idx=$((idx + 1))
    done

    ffmpeg -nostdin -y -loglevel error -f concat -safe 0 -i "${CONCAT_LIST}" \
        -c copy test_video.mp4
    echo "Built: test_video.mp4 (${#SAMPLE_CLIPS[@]} scenes, ${CLIP_SECONDS}s each)"
fi

echo "--- Done ---"
echo "Sample : $(pwd)/test_video.mp4"
echo "Note   : This use case requires no model; run the README samples directly."