feat(user/rand_media_pl.sh):Script to play random position of media

[BK-2020-03.git] / user / rand_media_pl.sh

#!/usr/bin/env bash
# Desc
#   - Finds audio and video files with specified extensions up to a max depth of 8.
#   - Uses ffprobe to measure their durations.
#   - Creates a playlist starting at a random location within the total runtime.
#   - Stores durations and file paths in a dotfile for faster subsequent runs.
#   - Prompts the user whether to use the cached data or regenerate it.
# Usage: rand_media_pl.sh [DIR]
# Version: 0.0.1
# Dependencies: Bash 4, ffprobe, mpv

yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails

# Configurable variables
SEARCH_DIR="$1";
MAX_DEPTH=8;
EXTENSIONS=("*.flac" "*.mp3" "*.opus" "*.m4a" "*.m4b" "*.mp4" "*.mkv" "*.webm");
CACHE_FILE=".playlist_cache";

declare -gA file_durations;
declare total_duration;

# Function to prompt the user
prompt_yes_no() {
    yell "STATUS:User input required.";
    local prompt_message="$1"
    local user_input
    while true; do
        read -rp "$prompt_message [y/n]: " user_input
        case "$user_input" in
            [Yy]*) return 0 ;;
            [Nn]*) return 1 ;;
            *) echo "Please answer yes or no." ;;
        esac;
    done;
};

# Function to find files with specified extensions
find_media_files() {
    yell "STATUS:Finding media files.";
    local find_cmd=("find" "-L" "$SEARCH_DIR" "-maxdepth" "$MAX_DEPTH" "-type" "f" "(");
    #declare -p find_cmd 1>&2; # debug
    for ext in "${EXTENSIONS[@]}"; do
        find_cmd+=("-iname" "$ext" "-o");
        #declare -p find_cmd 1>&2; # debug
    done;
    # Remove the last "-o" and add ")"
    unset 'find_cmd[-1]';
    find_cmd+=(")");
    "${find_cmd[@]}";
};

# Function to generate the playlist cache
generate_playlist_cache() {
    yell "Generating playlist cache. This may take a while..."
    # Initialize or empty the cache file
    if [[ ! -f "$CACHE_FILE" ]]; then
        touch "$CACHE_FILE";
    else
        rm "$CACHE_FILE";
    fi;
    
    total_duration=0
    while IFS= read -r file; do
        # Get the duration using ffprobe
        duration=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$file")
        if [[ -n "$duration" ]]; then
            # Append the file path and duration to the cache file
            printf "%s|%s\n" "$file" "$duration" >> "$CACHE_FILE";
            total_duration=$(echo "$total_duration + $duration" | bc);
        fi;
    done < <(find_media_files | sort);
    total_duration_s="$(echo "scale=1; ${total_duration} / 1" | bc -l)";
    total_duration_h="$(echo "scale=1; ${total_duration} / 3600" | bc -l)";
    
    yell "Total duration of playlist: ${total_duration_s} seconds. (${total_duration_h} hours.)";
};

# Function to read the playlist cache
read_playlist_cache() {
    # Input: file_durations  assoc. array
    #        total_duration  array
    yell "STATUS:Reading playlist cache.";
    
    total_duration=0
    while IFS='|' read -r file duration; do
        file_durations["$file"]="$duration"
        total_duration=$(echo "$total_duration + $duration" | bc)
    done < "$CACHE_FILE"
};

# Main script
if [[ -f "$CACHE_FILE" ]]; then
    if prompt_yes_no "Playlist cache detected. Do you want to use it? (Faster)"; then
        read_playlist_cache;
    else
        generate_playlist_cache;
        read_playlist_cache;
    fi;
else
    generate_playlist_cache;
    read_playlist_cache;
fi;

# Check if any files were found
if [[ ${#file_durations[@]} -eq 0 ]]; then
    declare -p file_durations 1>&2;
    die "FATAL:No media files found.";    
fi

# Get sorted list of files
mapfile -t sorted_files < <(printf '%s\n' "${!file_durations[@]}" | sort)

# Generate a random starting point within the total duration
random_point=$(awk -v max="$total_duration" 'BEGIN{srand(); print rand()*max}')

# Find the file and offset corresponding to the random starting point
accumulated_duration=0
for file in "${sorted_files[@]}"; do
    duration="${file_durations["$file"]}"
    new_accumulated_duration=$(echo "$accumulated_duration + $duration" | bc)
    if (( $(echo "$random_point < $new_accumulated_duration" | bc -l) )); then
        offset=$(echo "$random_point - $accumulated_duration" | bc)
        yell "Starting playback from $offset seconds into file: $file"

        # Create a playlist file
        playlist_file=$(mktemp)
        printf '%s\n' "${sorted_files[@]}" > "$playlist_file"

        # Start playback using mpv
        mpv --playlist="$playlist_file" --start="$offset" \
            --playlist-start=$(($(printf '%s\n' "${sorted_files[@]}" | grep -n "^$file$" | cut -d: -f1)-1))

        # Securely delete the playlist file
        if [[ -n "$playlist_file" && -f "$playlist_file" ]]; then
            rm "$playlist_file"; exit 0;
        else
            die "FATAL: playlist_file is either unset or not a valid file, skipping deletion.";
        fi;
    fi
    accumulated_duration="$new_accumulated_duration";
done

die "FATAL: Could not find file corresponding to random point.";