# Copyright (C) 2026 Rootiest
# SPDX-License-Identifier: AGPL-3.0-or-later

# SYNOPSIS
#   config-toggle [-h | --help]
#
# DESCRIPTION
#   Opens an interactive full-screen TUI for toggling the six opinionated
#   component categories (C1–C6) and the master disable variable without
#   having to remember variable names. Two scope tabs allow independent
#   per-scope configuration:
#
#     Universal — persists across all sessions (set -U / set -Ue)
#     Session   — active for the current shell only (set -g / set -eg)
#
#   Changes apply immediately on each Space keypress — no confirm step.
#   Always available regardless of __fish_config_opinionated state.
#
# ARGUMENTS
#   -h, --help  Print usage and exit
#
# RETURNS
#   0  Exited normally (q or Escape pressed)
#   1  Unknown flag passed
#
# EXAMPLE
#   config-toggle
function config-toggle --description 'Interactive TUI for toggling opinionated component settings'
    set -l c_head  (set_color --bold cyan)
    set -l c_cmd   (set_color --bold white)
    set -l c_flag  (set_color yellow)
    set -l c_dim   (set_color brblack)
    set -l c_err   (set_color red)
    set -l c_reset (set_color normal)

    # ── Argument parsing ──────────────────────────────────
    for arg in $argv
        switch $arg
            case -h --help
                echo "$c_head""Usage:$c_reset $c_cmd""config-toggle$c_reset $c_flag""[-h]$c_reset"
                echo
                echo "  Interactive TUI for toggling opinionated component categories."
                echo "  Changes apply immediately — no confirm step required."
                echo
                echo "$c_head""Navigation:$c_reset"
                echo "  $c_flag↑ ↓$c_reset or $c_flag""j k$c_reset    Move cursor up / down"
                echo "  $c_flag""Space$c_reset         Cycle: ON → OFF → DEFAULT → ON"
                echo "  $c_flag""Tab$c_reset           Switch scope (Universal ↔ Session)"
                echo "  $c_flag""q$c_reset / $c_flag""Q$c_reset         Exit"
                echo
                echo "$c_head""Scopes:$c_reset"
                echo "  $c_flag""Universal$c_reset   Persistent across all sessions ($c_dim""set -U$c_reset)"
                echo "  $c_flag""Session$c_reset     Current session only ($c_dim""set -g$c_reset)"
                return 0
            case '*'
                echo "$c_err""Unknown option: $arg$c_reset" >&2
                echo "Run $c_cmd""config-toggle --help$c_reset for usage." >&2
                return 1
        end
    end

    # ── Variable list (matches Panel Layout Reference) ────
    set -l vars \
        __fish_config_op_aliases \
        __fish_config_op_autoexec \
        __fish_config_op_overrides \
        __fish_config_op_integrations \
        __fish_config_op_logging \
        __fish_config_op_greeting \
        __fish_config_opinionated

    set -l cur_row   0           # 0–6
    set -l cur_scope universal   # or "session"
    set -l panel_h   14          # total panel lines

    # ── Terminal setup ────────────────────────────────────
    printf '\e[?25l'             # hide cursor
    trap 'printf "\e[?25h"; set -g __config_toggle_exit 1' INT

    # ── Initial draw ──────────────────────────────────────
    __config_toggle_draw $cur_row $cur_scope $vars

    # ── Event loop ────────────────────────────────────────
    # read -s -n 1 reads exactly one char without echoing it. Arrow keys send
    # ESC+[+letter as a 3-byte burst — after reading the ESC we immediately
    # read 2 more bytes which are already in the terminal buffer. Single-char
    # keys ('j','k',' ','q', Tab) are returned right away with no extra
    # blocking. NOTE: the nchars flag is -n; -k is not a valid read option.
    while true
        # Check for Ctrl-C signal (trap sets this flag)
        if set -q __config_toggle_exit
            set -eg __config_toggle_exit
            break
        end

        # -n 1 reads exactly one char; -s suppresses echo so keystrokes do
        # not garble the panel. If read fails (EOF / non-tty stdin) bail out
        # instead of spinning the redraw loop.
        read -s -n 1 -l key
        or break

        # Detect CSI escape sequences (arrow keys: ESC [ A/B)
        if test "$key" = \e
            read -s -n 1 -l key2
            if test "$key2" = "["
                read -s -n 1 -l key3
                set key "$key$key2$key3"   # \e[A or \e[B
            else
                # ESC + non-bracket (ALT+key or plain ESC): treat key2 as key
                set key $key2
            end
        end

        switch $key
            case \e\[A   # Up arrow
                set cur_row (math "max(0, $cur_row - 1)")
            case \e\[B   # Down arrow
                set cur_row (math "min(6, $cur_row + 1)")
            case k
                set cur_row (math "max(0, $cur_row - 1)")
            case j
                set cur_row (math "min(6, $cur_row + 1)")
            case \t      # Tab — switch scope
                if test $cur_scope = universal
                    set cur_scope session
                else
                    set cur_scope universal
                end
            case ' '     # Space — cycle and apply immediately
                set -l varname $vars[(math $cur_row + 1)]
                set -l cur_val (__config_toggle_get_val $varname $cur_scope)
                set -l next_val ""

                # Cycle: on → off → DEFAULT → on
                switch $cur_val
                    case on
                        set next_val off
                    case off
                        set next_val DEFAULT
                    case '*'   # DEFAULT or any unrecognised
                        set next_val on
                end

                # Apply immediately
                switch $cur_scope
                    case universal
                        switch $next_val
                            case on
                                set -U $varname on
                            case off
                                set -U $varname off
                            case DEFAULT
                                set -Ue $varname
                        end
                    case session
                        switch $next_val
                            case on
                                set -g $varname on
                            case off
                                set -g $varname off
                            case DEFAULT
                                set -eg $varname
                        end
                end
            case q Q
                break
        end

        # Redraw in place
        printf '\e[%dA\e[J' $panel_h
        __config_toggle_draw $cur_row $cur_scope $vars
    end

    # ── Cleanup ───────────────────────────────────────────
    trap - INT              # remove the signal handler
    printf '\e[?25h'        # restore cursor
end