{ config, pkgs, inputs, ... }:

let
  # Powerline separators, U+E0B0..U+E0B3.
  #
  # Written as escapes rather than literal glyphs. These are Private Use Area
  # codepoints: they render only with a patched font, they survive copy/paste
  # badly, and when they get stripped the loss is invisible, the config still
  # parses, the status bar just quietly loses its separators. Nix has no \u
  # escape of its own, but fromJSON does.
  sep = builtins.fromJSON ''
    {
      "right":     "\ue0b0",
      "rightThin": "\ue0b1",
      "left":      "\ue0b2",
      "leftThin":  "\ue0b3"
    }
  '';
in
{
  programs.tmux = {
    # defaults
    enable = true;
    prefix = "C-a";
    keyMode = "vi";
    mouse = true;

    # tmux-256color gives truecolor, italics and undercurl in nvim.
    terminal = "tmux-256color";

    # Default is 500ms. Causes lag you feel when leaving insert mode in nvim,
    # because tmux is waiting to see whether Esc starts an escape sequence.
    escapeTime = 10;

    # nvim autoread / :checktime react to focus.
    focusEvents = true;

    # History limit.
    historyLimit = 50000;

    # Window numbers matching the number row.
    baseIndex = 1;

    extraConfig = ''
      # Status keys
      set -g status-keys vi

      # Tell tmux the outer terminal can do 24-bit colour (tmux >= 3.2).
      set -sa terminal-features ",*:RGB"

      # Shift+Enter / extended keys
      # These make tmux forward CSI-u sequences unconditionally.
      # Needs tmux >= 3.5 for the format option,
      set -s extended-keys always
      set -s extended-keys-format csi-u
      set -as terminal-features '*:extkeys'

      # Status bar options
      set -g status-interval 5
      set -g status-justify left

      # Clock mode
      setw -g clock-mode-colour cyan

      # Colors
      set -g status-bg black
      set -g status-fg white

      # Key bindings
      bind r source-file ~/.config/tmux/tmux.conf \; display-message "tmux.conf reloaded"

      # Panel split and selection, new panes/windows inherit the cwd
      unbind %
      unbind '"'
      bind v split-window -v -c "#{pane_current_path}"
      bind c split-window -h -c "#{pane_current_path}"
      bind i new-window -c "#{pane_current_path}"
      bind -r b previous-window
      bind -r n next-window

      # Move around panes with hjkl
      bind h select-pane -L
      bind j select-pane -D
      bind k select-pane -U
      bind l select-pane -R

      # Resize panes
      bind -r H resize-pane -L 5
      bind -r J resize-pane -D 5
      bind -r K resize-pane -U 5
      bind -r L resize-pane -R 5

      # Wayland clipboard integration
      # Copy selection to both clipboard (Ctrl+V / Shift+Insert) and primary (middle-click)
      bind -T copy-mode-vi v send-keys -X begin-selection
      bind -T copy-mode-vi C-v send-keys -X rectangle-toggle
      bind -T copy-mode-vi y send-keys -X copy-pipe-and-cancel "wl-copy && wl-copy --primary"
      bind -T copy-mode-vi Enter send-keys -X copy-pipe-and-cancel "wl-copy && wl-copy --primary"
      bind -T copy-mode-vi MouseDragEnd1Pane send-keys -X copy-pipe-and-cancel "wl-copy && wl-copy --primary"
      # Uncomment if you want yanks to also travel over SSH via OSC52.
      # Locally redundant with wl-copy above.
      #set -g set-clipboard on

      # Kill commands
      bind q confirm-before -p "kill window #W? (y/n)" kill-window
      bind Q confirm-before -p "kill session #S? (y/n)" kill-session

      # Bars
      # This is the nord-tmux status line. #{prefix_highlight} came from that
      # theme's tmux-prefix-highlight integration -- a plugin you never loaded,
      # so the token expanded to nothing. tmux can do it natively. Commas inside
      # #{?...} are argument separators and have to be escaped as #, hence the
      # look of the style spec.
      set -g status-left-length 24
      set -g status-left "#[fg=black,bg=blue,bold] #{=20:session_name} #[fg=blue,bg=black,nobold,noitalics,nounderscore]${sep.right}"
      set -g status-right "#{?client_prefix,#[fg=black#,bg=yellow#,bold] ^A ,}#[fg=brightblack,bg=black,nobold,noitalics,nounderscore]${sep.left}#[fg=white,bg=brightblack] %Y-%m-%d #[fg=white,bg=brightblack,nobold,noitalics,nounderscore]${sep.leftThin}#[fg=white,bg=brightblack] %H:%M #[fg=cyan,bg=brightblack,nobold,noitalics,nounderscore]${sep.left}#[fg=black,bg=cyan,bold] #H "

      # Windows
      set -g window-status-format "#[fg=black,bg=brightblack,nobold,noitalics,nounderscore]${sep.right} #[fg=white,bg=brightblack]#I #[fg=white,bg=brightblack,nobold,noitalics,nounderscore]${sep.rightThin} #[fg=white,bg=brightblack]#W #F #[fg=brightblack,bg=black,nobold,noitalics,nounderscore]${sep.right}"
      set -g window-status-current-format "#[fg=black,bg=cyan,nobold,noitalics,nounderscore]${sep.right} #[fg=black,bg=cyan]#I #[fg=black,bg=cyan,nobold,noitalics,nounderscore]${sep.rightThin} #[fg=black,bg=cyan]#W #F #[fg=cyan,bg=black,nobold,noitalics,nounderscore]${sep.right}"
      set -g window-status-separator ""
    '';
  };
}