#!/usr/bin/env bash

set -euo pipefail
RED=$'\e[31m'
GREEN=$'\e[32m'
RESET=$'\e[0m'
usage() {
    cat <<EOF
Usage:
  $(basename "$0") <library-root> <book-list> [--dry-run|--find-missing]

Arguments:
  library-root   Root containing author/*/book/
  book-list      Text file containing:
                   rank|title|author|year

Options:
  --dry-run      Show what would be tagged without writing tags
  --find-missing List books from the ranking that were not found
EOF
    exit 1
}

[[ $# -ge 2 ]] || usage

ROOT="$1"
BOOKLIST="$2"
MODE="write"

case "${3:-}" in
    --dry-run)
        MODE="dryrun"
        ;;
    --find-missing)
        MODE="missing"
        ;;
    "")
        ;;
    *)
        usage
        ;;
esac

[[ -d "$ROOT" ]] || {
    echo "Library not found: $ROOT" >&2
    exit 1
}

[[ -f "$BOOKLIST" ]] || {
    echo "Book list not found: $BOOKLIST" >&2
    exit 1
}
echo "Using MODE $MODE"
echo "Libary: $ROOT"
echo "File: $BOOKLIST"

normalize() {
    echo "$1" |
        tr '[:upper:]' '[:lower:]' |
        sed -E "s/[^a-z0-9]+//g"
}

declare -A FOUND

while IFS='|' read -r RANK TITLE AUTHOR YEAR; do

    # Skip blank lines and comments
    [[ -z "$RANK" ]] && continue
    [[ "$RANK" =~ ^# ]] && continue

    NTITLE=$(normalize "$TITLE")
    NAUTHOR=$(normalize "$AUTHOR")

    MATCH=""

AUTHOR_PATH=$(find "$ROOT" -type d -iname "*$AUTHOR*" | head -n1)

[[ -z "$AUTHOR_PATH" ]] && continue

BOOK_PATH="$AUTHOR_PATH/book"
[[ -d "$BOOK_PATH" ]] || continue

while IFS= read -r FILE; do
    FILE_NAME="${FILE##*/}"
    FILE_BASE="${FILE_NAME%.*}"

    echo "Checking: $FILE_BASE"

    if [[ "$(normalize "$FILE_BASE")" == "$NTITLE" ]]; then
        MATCH="$FILE"
        break
    fi
done < <(find "$BOOK_PATH" -maxdepth 1 -type f)
    if [[ -n "$MATCH" ]]; then
        FOUND["$RANK"]=1

        GROUP="Sci Fi Top 100 Books #$RANK"

        case "$MODE" in
            dryrun)
                echo "Would tag:"
                echo "  File : $MATCH"
                echo "  Album: $GROUP"
                echo "  Year : $YEAR"
                echo
                ;;

            write)
                echo "Tagging: $MATCH"

                id3v2 \
                    --TALB "$GROUP" \
                    --TYER "$YEAR" \
                    "$MATCH"
                ;;

            missing)
                ;;
        esac
    fi

done < "$BOOKLIST"

if [[ "$MODE" == "missing" ]]; then
    while IFS='|' read -r RANK TITLE AUTHOR YEAR; do
        [[ -z "$RANK" ]] && continue
        [[ "$RANK" =~ ^# ]] && continue

        if [[ -n "${FOUND[$RANK]:-}" ]]; then
            printf "${GREEN}FOUND${RESET}   #%3d | %s | %s | %s\n" \
                "$RANK" "$TITLE" "$AUTHOR" "$YEAR"
        else
            printf "${RED}MISSING${RESET} #%3d | %s | %s | %s\n" \
                "$RANK" "$TITLE" "$AUTHOR" "$YEAR"
        fi
    done < "$BOOKLIST"
fi