#!/usr/bin/env bash
set -euo pipefail

###############################################################################
# SREAD — Browse research library with nnn, open in Zathura
#
# Maintainer:   Kris Yotam <krisyotam@pm.me>
# License:      MIT
# Created:      2026-02-15
#
# Categories:
#   Papers        → ~/research/library/papers/
#   Texts         → ~/research/library/texts/
#   Primary Texts → ~/research/library/primary-texts/
#   Books         → ~/Calibre Library/
#
# Select a category, then browse with nnn. Enter on any file opens in Zathura.
###############################################################################

###############################################################################
# config
###############################################################################

LIBRARY="$HOME/research/library"
CALIBRE="$HOME/Calibre Library"

declare -A CATEGORIES=(
    [papers]="$LIBRARY/papers"
    [texts]="$LIBRARY/texts"
    [primary-texts]="$LIBRARY/primary-texts"
    [books]="$CALIBRE"
)

CATEGORY_ORDER=(papers texts primary-texts books)

###############################################################################
# helpers
###############################################################################

have_cmd() { command -v "$1" >/dev/null 2>&1; }

die() { echo "ERROR: $1" >&2; exit 1; }

have_cmd fzf     || die "fzf not found"
have_cmd nnn     || die "nnn not found"
have_cmd zathura || die "zathura not found"

###############################################################################
# ui
###############################################################################

print_banner() {
    local cols
    cols="$(tput cols 2>/dev/null || echo 80)"

    if have_cmd figlet; then
        figlet -w "$cols" -f big "LIBRARY" 2>/dev/null \
            || figlet -w "$cols" "LIBRARY"
    else
        echo "LIBRARY"
    fi

    echo
    echo "  research library"
    echo "  curator: Kris Yotam"
    echo "  script: sread"
    echo
    echo "  \"A room without books is like a body without a soul.\""
    echo "  — Marcus Tullius Cicero"
    echo
}

###############################################################################
# calibre — flat "Title — Author" list via metadata.db, opened with fzf
###############################################################################

browse_calibre() {
    local db="$CALIBRE/metadata.db"
    if [ ! -f "$db" ]; then
        echo "Calibre metadata.db not found"
        read -rp "Press Enter..." _
        return
    fi

    # Query all books: title|author|relative-path|format|data-name
    local entries
    entries=$(sqlite3 "$db" "
        SELECT b.title, COALESCE(a.name, 'Unknown'), b.path,
               COALESCE(d.format, 'pdf'), COALESCE(d.name, b.title)
        FROM books b
        LEFT JOIN books_authors_link bal ON bal.book = b.id
        LEFT JOIN authors a ON a.id = bal.author
        LEFT JOIN data d ON d.book = b.id
        WHERE d.format IS NOT NULL
        ORDER BY b.title
    " 2>/dev/null)

    if [ -z "$entries" ]; then
        echo "No books in Calibre Library"
        read -rp "Press Enter..." _
        return
    fi

    # Build display lines and parallel path array
    local -a lines=()
    local -a paths=()

    while IFS='|' read -r title author relpath fmt fname; do
        [ -z "$title" ] && continue
        local ext
        ext=$(echo "$fmt" | tr '[:upper:]' '[:lower:]')
        lines+=("${title} — ${author}")
        paths+=("$CALIBRE/$relpath/$fname.$ext")
    done <<< "$entries"

    # fzf selection
    local choice
    choice=$(printf '%s\n' "${lines[@]}" | fzf --prompt="book> " --reverse) || return

    # Find matching index
    local i
    for i in "${!lines[@]}"; do
        if [[ "${lines[$i]}" == "$choice" ]]; then
            local file="${paths[$i]}"
            if [ -f "$file" ]; then
                zathura "$file" &>/dev/null & disown
            else
                echo "File not found: $(basename "$file")"
                read -rp "Press Enter..." _
            fi
            return
        fi
    done
}

###############################################################################
# main
###############################################################################

main() {
    clear
    print_banner

    while true; do
        # Select category via fzf
        local category
        category="$(
            printf "%s\n" "${CATEGORY_ORDER[@]}" "quit" |
            fzf --prompt="section> " --height=8 --reverse
        )" || exit 0

        [[ "$category" == "quit" ]] && exit 0

        if [[ "$category" == "books" ]]; then
            # Calibre: flat fzf list from metadata.db
            browse_calibre
        else
            local target="${CATEGORIES[$category]}"
            if [[ ! -d "$target" ]]; then
                echo "Directory not found: $target"
                read -rp "Press Enter..." _
                clear
                print_banner
                continue
            fi

            # Launch nnn with Zathura opener, hidden files off
            NNN_OPTS="deQ" \
            NNN_OPENER="$HOME/.local/bin/nnn-zathura" \
            NNN_FALLBACK_OPENER="${NNN_OPENER:-xdg-open}" \
                nnn "$target"
        fi

        # Loop back to category selection
        clear
        print_banner
    done
}

main