#!/bin/bash
# 4-seasons.sh — create one daily clip from yesterday's images, sized to its
# share of the corresponding Vivaldi movement's music duration.
# Run once per day (e.g. from cron at 01:00).

set -euo pipefail
set -x

# ── Configuration ──────────────────────────────────────────────────────────────
base_dir="/home/motion/drives/local-2tb"
music_base_dir="$base_dir/music/4 Seasons"
# Fallback: use music/ directory next to this script (repo copy)
[ ! -d "$music_base_dir" ] && music_base_dir="$(dirname "$(realpath "$0")")/music"

TARGET_W=1280
TARGET_H=720

# ── Date setup ────────────────────────────────────────────────────────────────
yesterday=$(date --date="yesterday" +%Y-%m-%d)
day_of_year=$(date --date="$yesterday" +%j | sed 's/^0*//')   # strip leading zeros

# ── Season / movement detection ────────────────────────────────────────────────
if   [ "$day_of_year" -ge 80  ] && [ "$day_of_year" -le 172 ]; then
    season="Spring"; season_start=80;  days_in_season=93
elif [ "$day_of_year" -ge 173 ] && [ "$day_of_year" -le 264 ]; then
    season="Summer"; season_start=173; days_in_season=92
elif [ "$day_of_year" -ge 265 ] && [ "$day_of_year" -le 355 ]; then
    season="Autumn"; season_start=265; days_in_season=91
else
    season="Winter"; days_in_season=90
    if [ "$day_of_year" -ge 356 ]; then season_start=356; else season_start=0; fi
fi

# Day within the season (1-based)
if [ "$season" = "Winter" ] && [ "$day_of_year" -lt 80 ]; then
    day_of_season=$(( day_of_year + 365 - 355 ))
elif [ "$season" = "Winter" ]; then
    day_of_season=$(( day_of_year - 355 ))
else
    day_of_season=$(( day_of_year - season_start + 1 ))
fi

# Each season: three movements of ~30 days; Mvt 3 takes the remainder
if   [ "$day_of_season" -le 30 ]; then movement_num=1; days_in_movement=30
elif [ "$day_of_season" -le 60 ]; then movement_num=2; days_in_movement=30
else                                    movement_num=3; days_in_movement=$(( days_in_season - 60 ))
fi

echo "Date=$yesterday  Season=$season  Mvt=$movement_num  DayOfSeason=$day_of_season  DaysInMvt=$days_in_movement"

# ── Locate music file ─────────────────────────────────────────────────────────
music_file=$(find "$music_base_dir" -type f -iname "*${season}*Mvt*${movement_num}*" | sort | head -n 1)
if [ -z "$music_file" ] || [ ! -f "$music_file" ]; then
    echo "ERROR: Music file not found for $season Mvt $movement_num in $music_base_dir"
    exit 1
fi
music_duration=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$music_file")
echo "Music: $(basename "$music_file")  ($music_duration s)"

# Each daily clip should cover music_duration / days_in_movement seconds so that
# the full movement montage sums to exactly the music duration.
target_duration_per_video=$(echo "scale=6; $music_duration / $days_in_movement" | bc)
echo "Target duration per daily clip: $target_duration_per_video s"

# ── Locate images ─────────────────────────────────────────────────────────────
script_name=$(basename "$(dirname "$(realpath "$0")")" | cut -d'-' -f1)
image_dir="$base_dir/$script_name/$yesterday"

if [ ! -d "$image_dir" ]; then
    echo "WARNING: Image directory $image_dir not found for $yesterday — skipping."
    exit 0
fi

total_images=$(find "$image_dir" -type f -name "*.jpg" | wc -l)
if [ "$total_images" -lt 1 ]; then
    echo "WARNING: No images in $image_dir for $yesterday — skipping."
    exit 0
fi

# ── Prepare output directory ──────────────────────────────────────────────────
output_dir="$base_dir/movies/$script_name/$season/Mvt$movement_num"
mkdir -p "$output_dir"

# ── Build sorted image list ────────────────────────────────────────────────────
temp_file=$(mktemp --suffix=.txt)
trap 'rm -f "$temp_file" "$temp_video"' EXIT

find "$image_dir" -type f -name "*.jpg" | sort | while read -r img; do
    echo "file '$img'"
done > "$temp_file"

num_images=$(wc -l < "$temp_file")
echo "Images: $num_images"

# ── Step 1: Build raw video at default frame rate ─────────────────────────────
temp_video="$output_dir/${yesterday}_Mvt${movement_num}-temp.mp4"
echo "Creating raw video..."
ffmpeg -loglevel warning \
    -f concat -safe 0 -i "$temp_file" \
    -c:v libx264 -pix_fmt yuv420p -crf 28 -vsync 2 -an \
    -y "$temp_video"

raw_duration=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$temp_video")
echo "Raw video duration: $raw_duration s"

# ── Step 2: Speed-adjust to target duration + normalise resolution ─────────────
speed_factor=$(echo "scale=6; $raw_duration / $target_duration_per_video" | bc)
echo "Speed factor: $speed_factor"

final_file="$output_dir/${yesterday}_Mvt${movement_num}-Day${day_of_season}of${days_in_movement}-final.mp4"
ffmpeg -loglevel warning \
    -i "$temp_video" \
    -vf "setpts=PTS/$speed_factor,\
scale=${TARGET_W}:${TARGET_H}:force_original_aspect_ratio=decrease,\
pad=${TARGET_W}:${TARGET_H}:(ow-iw)/2:(oh-ih)/2,setsar=1" \
    -c:v libx264 -pix_fmt yuv420p -crf 26 \
    -t "$target_duration_per_video" \
    -y "$final_file"

rm "$temp_video"

adjusted_duration=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$final_file")
echo "Daily clip created: $final_file  ($adjusted_duration s)"