#!/usr/bin/env bash
set -euo pipefail
# POS: tree — Show the pos CLI command tree: categories, commands, and subcommands
# POS_FLAGS: --depth

source "$(dirname "$0")/../lib/common.sh" 2>/dev/null || source "$(dirname "$0")/common.sh"

usage() {
    cat <<EOF
Usage: pos tree [--depth N]

Print the `pos` command tree: every category, command, and subcommand the
dispatcher can reach, annotated with each tool's # POS: description.

  pos tree            Full command tree
  pos tree --depth N  Limit nesting depth (1 = root only)
  pos tree --help     This help
EOF
    exit 0
}

depth=""
case "${1:-}" in
    -h|--help) usage ;;
    --depth)
        [ $# -ge 2 ] || err "--depth requires a number"
        depth="$2"
        [[ "$depth" =~ ^[0-9]+$ ]] || err "--depth must be a number"
        shift 2
        ;;
    -*) err "unknown flag: $1" ;;
esac

self="$(cd "$(dirname "$0")" && pwd)"

declare -A children meta
maxw=0

# add <parent> <word> <type> <desc> — parent "/" is the root.
add() {
    local parent="$1" word="$2" type="$3" desc="$4" path
    if [ "$parent" = "/" ]; then path="$word"; else path="$parent/$word"; fi
    children["$parent"]+=" $word"
    meta["$path"]="$type|$desc"
}

for f in "$self"/pos-*; do
    [ -x "$f" ] || continue
    name="${f##*/pos-}"
    desc="$(sed -n '/^# POS: /{s/^# POS: //;p;q}' "$f")"
    desc="${desc#*— }"
    sc="$(sed -n '/^# POS_SUBCMDS: /{s/^# POS_SUBCMDS: //;p;q}' "$f")"
    words=(${name//-/ })
    parent="/"
    for ((i=0; i<${#words[@]}; i++)); do
        word="${words[$i]}"
        if [ "$parent" = "/" ]; then path="$word"; else path="$parent/$word"; fi
        if [ $((i + 1)) -eq ${#words[@]} ]; then
            add "$parent" "$word" "tool" "$desc"
        else
            [ -n "${meta[$path]:-}" ] || add "$parent" "$word" "cat" ""
        fi
        parent="$path"
    done
    for s in $sc; do
        add "$parent" "$s" "sub" ""
    done
done

# pad = widest "pos <full path>" leaf, so descriptions align
for p in "${!meta[@]}"; do
    case "${meta[$p]%%|*}" in
        tool|sub)
            len=$(( ${#p} + 4 ))
            [ "$len" -gt "$maxw" ] && maxw=$len
            ;;
    esac
done

render() {
    local parent="$1" prefix="$2" lvl="$3"
    if [ -n "$depth" ] && [ "$lvl" -ge "$depth" ]; then return; fi
    local -a kids
    mapfile -t kids < <(printf '%s\n' ${children[$parent]:-} | sort -u)
    local i word path type desc conn nextpref last
    for ((i=0; i<${#kids[@]}; i++)); do
        word="${kids[$i]}"
        if [ "$parent" = "/" ]; then path="$word"; else path="$parent/$word"; fi
        last=$(( i == ${#kids[@]} - 1 ))
        if [ "$last" -eq 1 ]; then conn="└── "; nextpref="$prefix    "; else conn="├── "; nextpref="$prefix│   "; fi
        type="${meta[$path]%%|*}"
        desc="${meta[$path]#*|}"
        case "$type" in
            cat)
                printf '%s%s%s/\n' "$prefix" "$conn" "$word"
                render "$path" "$nextpref" $((lvl+1))
                ;;
            tool)
                printf '%s%s%-*s# %s\n' "$prefix" "$conn" "$((maxw+1))" "pos ${path//\// }" "$desc"
                if [ -n "${children[$path]:-}" ]; then
                    render "$path" "$nextpref" $((lvl+1))
                fi
                ;;
            sub)
                printf '%s%s%s\n' "$prefix" "$conn" "pos ${path//\// }"
                ;;
        esac
    done
}

printf 'pos\n'
render "/" "" 1