#!/usr/bin/bash
#
# Show every keyboard shortcut in the session, and what each one runs.
#
# WHY THIS EXISTS
# ---------------
# COSMIC has no keyboard reference. cosmic-settings lists shortcuts in a
# scrolling pane behind three clicks, which is where you go to *change* one, not
# where you go to remember one mid-task. Hyprland desktops all ship a cheatsheet
# on a key and a bar click for exactly that reason, and this is that.
#
# WHERE THE BINDINGS COME FROM, AND WHY NOT cosmic.conf
# -----------------------------------------------------
# The obvious implementation reads cosmic.conf, and it would be wrong. This
# machine's cosmic.conf declares six bindings. The session answers to 122. The
# other 116 are COSMIC's own defaults, which the fork does not restate because
# it has no reason to -- Super+Q closes a window whether or not anybody wrote it
# down. A cheatsheet showing six entries would not look broken; it would look
# complete, and it would be missing every window, workspace and media key on the
# machine. That is a worse failure than not having the feature.
#
# So the sources are the three RON files the compositor actually reads:
#
#   /usr/share/cosmic/.../Shortcuts/v1/defaults   116 COSMIC built-ins
#   ~/.config/cosmic/.../Shortcuts/v1/custom        6 ours, projected from
#                                                     cosmic.conf by cosmic-conf
#   /usr/share/cosmic/.../Shortcuts/v1/system_actions
#                                                   what System(X) actually runs
#
# custom wins over defaults on a collision, matching the order the compositor
# merges them, so a rebound key is listed once with the binding in force.
#
# system_actions is what makes this answer the question that was asked. A
# default reads `System(Screenshot)`, which names an action and not a program;
# system_actions maps that to `cosmic-screenshot`. Without it a third of the
# list would name internal actions rather than the applications they launch.
#
# THE PARSER
# ----------
# These are RON files, and this reads them with a regex, which deserves a
# defence. The alternative is a `cosmic-conf binds` subcommand, which would be
# the principled home for this -- cosmic-conf already has the schema and the
# bind grammar. That is a compiled change and a full package build, and this
# feature does not need one: the files are one binding per line, and the shape
# has not moved. The cost of being wrong here is a mangled row in a reference
# window, not a broken keybinding, because nothing downstream consumes this.
#
# If the format does move, the failure is visible immediately and loudly: the
# count check below refuses to show a list it could not parse.

set -uo pipefail

SYS_DIR=/usr/share/cosmic/com.system76.CosmicSettings.Shortcuts/v1
USER_DIR="${XDG_CONFIG_HOME:-$HOME/.config}/cosmic/com.system76.CosmicSettings.Shortcuts/v1"

command -v rofi >/dev/null 2>&1 || {
    printf 'hyprcosmic-keybinds: rofi is not installed\n' >&2
    exit 1
}

# Errors go to a rofi dialog as well as stderr: the two ways in are a keybinding
# and a bar click, and neither has a terminal to read stderr from. Same reasoning
# as hyprcosmic-powermenu.
fail() {
    printf 'hyprcosmic-keybinds: %s\n' "$*" >&2
    rofi -e "$*" >/dev/null 2>&1 || :
    exit 1
}

[[ -r "$SYS_DIR/defaults" ]] ||
    fail "cannot read $SYS_DIR/defaults, so the built-in shortcuts are unknown"

# Resolve System(X) to the command it runs, as "X<tab>command" pairs.
#
# system_actions carries /// doc comments and commented-out entries for actions
# that exist in the enum but are not wired up (KeyboardBrightnessUp is one), so
# this matches only lines that are a bare name followed by a quoted string.
system_actions() {
    [[ -r "$SYS_DIR/system_actions" ]] || return 0
    sed -nE 's/^[[:space:]]*([A-Za-z]+):[[:space:]]*"(.*)",?[[:space:]]*$/\1\t\2/p' \
        "$SYS_DIR/system_actions"
}

# One binding per line, as "modifiers<tab>key<tab>action".
#
# Two shapes appear. The usual one carries a key:
#     (modifiers: [Super, Shift], key: "Escape"): System(LogOut),
# and a modifier-only binding has none at all:
#     (modifiers: [Super]): Spawn("rofi -show drun"),
# The second is how Super alone opens the launcher, so dropping it would lose
# the single most used binding on the machine.
bindings() {
    sed -nE \
        -e 's/^[[:space:]]*\(modifiers:[[:space:]]*\[([^]]*)\],[[:space:]]*key:[[:space:]]*"([^"]*)"\):[[:space:]]*(.*),[[:space:]]*$/\1\t\2\t\3/p' \
        -e 's/^[[:space:]]*\(modifiers:[[:space:]]*\[([^]]*)\]\):[[:space:]]*(.*),[[:space:]]*$/\1\t\t\2/p' \
        "$1"
}

actions_tsv="$(system_actions)"

# custom is read second so that its rows overwrite defaults in the map below.
# Missing is normal, not an error: a session with no custom bindings has no such
# file, and every default still applies.
raw="$(bindings "$SYS_DIR/defaults")"
if [[ -r "$USER_DIR/custom" ]]; then
    raw+=$'\n'"$(bindings "$USER_DIR/custom")"
fi

[[ -n "${raw//[[:space:]]/}" ]] ||
    fail "parsed no shortcuts at all from $SYS_DIR/defaults; the file format has changed"

rendered="$(
    LC_ALL=C awk -F'\t' -v actions="$actions_tsv" '
    BEGIN {
        # System(X) -> command, from system_actions.
        n = split(actions, lines, "\n")
        for (i = 1; i <= n; i++) {
            if (split(lines[i], kv, "\t") == 2) cmd[kv[1]] = kv[2]
        }
    }

    # Turn CamelCase into words so an action reads as a description rather than
    # an identifier: MoveToWorkspace -> "move to workspace". Applied only to the
    # action name, never to a command, which must stay verbatim to be typed.
    function words(s,   out) {
        out = s
        gsub(/([a-z0-9])([A-Z])/, "\\1 \\2", out)
        return tolower(out)
    }

    # Super is written first and Shift last, so that chords sort and read the
    # way they are pressed rather than the way the RON happened to list them.
    function order(m) {
        if (m == "Super") return 1
        if (m == "Ctrl")  return 2
        if (m == "Alt")   return 3
        if (m == "Shift") return 4
        return 5
    }

    {
        mods = $1; key = $2; action = $3
        if (action == "") next

        # "Super, Alt" -> "Super + Alt", in a fixed order.
        cnt = split(mods, m, /,[[:space:]]*/)
        for (i = 1; i <= cnt; i++) gsub(/^[[:space:]]+|[[:space:]]+$/, "", m[i])
        for (i = 1; i < cnt; i++)
            for (j = i + 1; j <= cnt; j++)
                if (order(m[j]) < order(m[i])) { t = m[i]; m[i] = m[j]; m[j] = t }

        chord = ""
        for (i = 1; i <= cnt; i++) chord = chord (chord == "" ? "" : " + ") m[i]
        if (key != "") chord = chord (chord == "" ? "" : " + ") key

        # Spawn("cmd") is a command as written in cosmic.conf.
        # System(X) is an action name that system_actions turns into a command.
        # Everything else is internal to the compositor and has no command; the
        # action itself is the honest answer, and inventing a program name for
        # Focus(Left) would be a lie.
        what = ""
        if (action ~ /^Spawn\(".*"\)$/) {
            what = substr(action, 8, length(action) - 9)
        } else if (action ~ /^System\(/) {
            name = action
            sub(/^System\(/, "", name); sub(/\)$/, "", name)
            what = (name in cmd) ? cmd[name] : words(name)
        } else if (action ~ /\(/) {
            name = action; arg = action
            sub(/\(.*$/, "", name)
            sub(/^[^(]*\(/, "", arg); sub(/\)$/, "", arg)
            what = words(name) " " arg
        } else {
            what = words(action)
        }

        # Last write wins, which is why custom is appended after defaults.
        seen[chord] = what
        if (!(chord in orderkey)) orderkey[chord] = ++seq
    }

    END {
        for (c in seen) printf "%d\t%s\t%s\n", orderkey[c], c, seen[c]
    }
    ' <<<"$raw" | sort -n | cut -f2-
)"

count="$(grep -c . <<<"$rendered")"
((count > 0)) || fail "every shortcut line failed to parse; the RON format has changed"

# Column-aligned so the chords form a readable left edge. Done here rather than
# in awk because the width has to be measured across the whole set first.
width="$(cut -f1 <<<"$rendered" | LC_ALL=C awk '{ if (length($0) > w) w = length($0) } END { print w }')"

# -dmenu rather than a static window, so the list is filterable: 122 bindings is
# more than fits on a screen, and typing "workspace" is how you actually use
# this. No theme arguments, so ~/.config/rofi/config.rasi applies and it matches
# the launcher and the power menu.
#
# The selection is discarded. This is a reference, not a menu -- there is no
# sensible action for "you picked Super + Q", and running the bound command on
# Return would make an accidental keypress close a window from a help screen.
LC_ALL=C awk -F'\t' -v w="$width" '{ printf "%-*s   %s\n", w, $1, $2 }' <<<"$rendered" |
    rofi -dmenu -i -no-custom -no-show-icons -p "keys" \
         -mesg "$count shortcuts" >/dev/null 2>&1 || :