#!/usr/bin/env bash
# The helper of a share: laid here by the fabric node that serves this directory at https://files.playground.balcony.codes, and laid again by it
# whenever that address moves. Run it from anywhere; it reads nothing but where it lies.
#
#   fab-share.bash url <path>...    the address a file or directory beneath this share is served at
#   fab-share.bash list [<dir>]     every file beneath a directory of the share, with its address
#   fab-share.bash where            this share's directory and its address
#
# Files and directories whose names begin with a dot are not served.
set -euo pipefail
shopt -s inherit_errexit

share_url='https://files.playground.balcony.codes'

die() {
    printf 'fab-share: %s\n' "$*" >&2
    exit 1
}

# The share is the directory this script lies in, however it was called.
with_share() {
    local share_dir
    share_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd -P)"
    "$@"
}

# A path, absolute or relative to where the call was made, as the share serves it: its part beneath the share.
with_held() {
    local given="$1" path held
    shift
    path="$(realpath -m -- "$given")"
    case "$path/" in
    "$share_dir"/*) ;;
    *) die "$given is not beneath $share_dir" ;;
    esac
    held="${path#"$share_dir"}"
    "$@"
}

do_url() { printf '%s%s\n' "$share_url" "$(do_encoded "${held:-/}")"; }

# A path as a URL carries it: every byte but the unreserved ones and the slash percent-encoded.
do_encoded() {
    local LC_ALL=C text="$1" out="" char i
    for ((i = 0; i < ${#text}; i++)); do
        char="${text:i:1}"
        case "$char" in
        [A-Za-z0-9._~/-]) out+="$char" ;;
        *) printf -v char '%%%02X' "'$char" && out+="$char" ;;
        esac
    done
    printf '%s' "$out"
}

do_listed() { printf '%s\t%s\n' "$held" "$(do_url)"; }

goal__url() {
    (($#)) || die "url <path>..."
    local one
    for one in "$@"; do with_held "$one" do_url; done
}

goal__list() {
    local dir file
    dir="$(realpath -m -- "${1:-$share_dir}")"
    while IFS= read -r -d '' file; do
        with_held "$file" do_listed
    done < <(find "$dir" -mindepth 1 -name '.*' -prune -o -type f -print0 | sort -z)
}

goal__where() { printf '%s\t%s/\n' "$share_dir" "$share_url"; }

goal() {
    local verb="${1:-}"
    declare -F "goal__$verb" >/dev/null || die "a verb: url <path>..., list [<dir>], where"
    shift
    "goal__$verb" "$@"
}

with_share goal "$@"