# ~/.tilemux.conf - i3-like tiling for tmux
# Tested design target: tmux 3.6
#
# Main modifier: Alt (tmux calls it Meta, written M-).
# These bindings do NOT require the normal tmux prefix.
#
# Layout model: a window is a row of columns, each column a stack of panes.
#   Alt+Shift+left/right   move the pane to the neighbouring column
#   Alt+Shift+up/down      move the pane within its own column
#   at the window edge     the pane leaves its column and becomes a
#                          full-width row or full-height column of its own
#   Alt+m then direction   merge the pane into the neighbour, the way back
#
# Quick help: Alt+?

##### General ###############################################################

# Treat tmux windows like numbered workspaces.
set -g base-index 1
setw -g pane-base-index 1
set -g renumber-windows off

# Put status at the top.
set -g status-position top

# Alt must not be read as Escape then a key. This is the default on 3.6;
# setting it explicitly covers older tmux.
set -sg escape-time 10

# Keep a normal tmux prefix as an escape hatch.
unbind C-b
set -g prefix C-Space
bind C-Space send-prefix

set -g history-limit 50000
set -g focus-events on


##### Help: Alt+? ###########################################################
# Shift+/ produces ?, so Alt+? is M-? in tmux notation.

bind -n 'M-?' display-popup -E -w 76 -h 23 -T ' tilemux - Enter to close ' 'printf "%s\n" \
	"  WORKSPACES" \
	"    Alt+1..9,0              select/create workspace (0 is workspace 10)" \
	"    Alt+Shift+1..9,0        move pane there; a lone pane takes its window" \
	"    Ctrl+Alt+Left/Right     previous/next workspace" \
	"    Alt+Tab, Alt+backtick   last workspace" \
	"    Alt+n                   rename workspace" \
	"  FOCUS" \
	"    Alt+h/j/k/l or Arrow    focus left/down/up/right" \
	"    Alt+o                   last pane" \
	"  MOVE PANE" \
	"    Alt+Shift+h/j/k/l/Arrow left/right to the next column, up/down in it" \
	"                            at the window edge: a full row or column" \
	"    Alt+m then a direction  merge into the neighbour, the way back" \
	"  PANES" \
	"    Alt+Enter               new pane, split along the longer side" \
	"    Alt+b / Alt+v           split left|right / top|bottom" \
	"    Alt+f / Alt+Shift+q     fullscreen/zoom / kill pane" \
	"    Alt+e                   cycle tmux preset layouts" \
	"    Alt+r                   resize mode: hjkl/arrows, = evens, Enter/Esc" \
	"    Ctrl+Space              normal tmux prefix (Alt+? shows this list)"; read _'


##### Focus panes: Alt+hjkl AND Alt+arrows ##################################

bind -n M-h select-pane -L
bind -n M-j select-pane -D
bind -n M-k select-pane -U
bind -n M-l select-pane -R

bind -n M-Left  select-pane -L
bind -n M-Down  select-pane -D
bind -n M-Up    select-pane -U
bind -n M-Right select-pane -R

# Back to the pane focused before this one.
bind -n M-o last-pane


##### Move panes: Alt+Shift+hjkl AND Alt+Shift+arrows #######################
#
# tmux exposes pane geometry to formats but not its layout tree, so the
# rules are expressed in geometry:
#
#   left/right  pane is as tall as the window -> it is a whole column, so
#                                                swap it with the neighbour
#               otherwise                     -> leave this column and join
#                                                the neighbouring one
#               nothing in that direction     -> become a full-height column
#                                                at that edge of the window
#
#   up/down     a pane in that direction      -> swap with it
#               nothing in that direction     -> become a full-width row at
#                                                that edge of the window
#
# A pane that already spans the window along the relevant axis does nothing.
# That is what stops repeated presses from nesting forever.
#
# Notes:
#   - {left-of} and friends WRAP AROUND the window, so every use of them is
#     guarded by the matching pane_at_* flag.
#   - tmux takes the source of a join or swap from the marked pane whenever
#     one is set, whatever -s says, so the mark is cleared first, even when
#     the rules below then decide to do nothing. Marks belong to the join
#     and swap workflow these bindings replace.
#   - the pane joins above the neighbour, or below it when moving out of the
#     bottom row, so it keeps roughly the row it came from.
#   - select-layout -E gives every pane in the destination column an equal
#     share, the way i3 does when a window joins a container.
#   - the logic lives in command aliases because tmux cannot bind two keys
#     to one command list any other way. Aliases take no arguments.
#   - a zoomed pane covers the window, so every rule would read as "already
#     spans everything" and do nothing. Moving unzooms first, which is what
#     select-pane does for focus anyway.

set -s command-alias[100] "tile-left=select-pane -M ; \
if -F '#{window_zoomed_flag}' { resize-pane -Z } ; \
if -F '#{pane_at_left}' { \
	if -F '#{&&:#{!=:#{window_panes},1},#{!=:#{pane_height},#{window_height}}}' { \
		join-pane -h -f -b -t '{next}' ; select-layout -E \
	} \
} { \
	if -F '#{==:#{pane_height},#{window_height}}' { \
		swap-pane -d -t '{left-of}' \
	} { \
		if -F '#{pane_at_bottom}' { \
			join-pane -v -t '{left-of}' ; select-layout -E \
		} { \
			join-pane -v -b -t '{left-of}' ; select-layout -E \
		} \
	} \
}"

set -s command-alias[101] "tile-right=select-pane -M ; \
if -F '#{window_zoomed_flag}' { resize-pane -Z } ; \
if -F '#{pane_at_right}' { \
	if -F '#{&&:#{!=:#{window_panes},1},#{!=:#{pane_height},#{window_height}}}' { \
		join-pane -h -f -t '{next}' ; select-layout -E \
	} \
} { \
	if -F '#{==:#{pane_height},#{window_height}}' { \
		swap-pane -d -t '{right-of}' \
	} { \
		if -F '#{pane_at_bottom}' { \
			join-pane -v -t '{right-of}' ; select-layout -E \
		} { \
			join-pane -v -b -t '{right-of}' ; select-layout -E \
		} \
	} \
}"

set -s command-alias[102] "tile-up=select-pane -M ; \
if -F '#{window_zoomed_flag}' { resize-pane -Z } ; \
if -F '#{pane_at_top}' { \
	if -F '#{&&:#{!=:#{window_panes},1},#{!=:#{pane_width},#{window_width}}}' { \
		join-pane -v -f -b -t '{next}' ; select-layout -E \
	} \
} { \
	swap-pane -d -t '{up-of}' \
}"

set -s command-alias[103] "tile-down=select-pane -M ; \
if -F '#{window_zoomed_flag}' { resize-pane -Z } ; \
if -F '#{pane_at_bottom}' { \
	if -F '#{&&:#{!=:#{window_panes},1},#{!=:#{pane_width},#{window_width}}}' { \
		join-pane -v -f -t '{next}' ; select-layout -E \
	} \
} { \
	swap-pane -d -t '{down-of}' \
}"

bind -n M-H tile-left
bind -n M-J tile-down
bind -n M-K tile-up
bind -n M-L tile-right

bind -n M-S-Left  tile-left
bind -n M-S-Down  tile-down
bind -n M-S-Up    tile-up
bind -n M-S-Right tile-right


##### Merge into the neighbour: Alt+m, then a direction #####################
#
# Alt+Shift+direction pushes a pane out of its column, and once a pane is a
# whole column of its own it swaps with its neighbours instead of joining
# them. This is the way back in: merge always joins the neighbouring pane,
# whatever the shape of either of them.
#
#   Alt+m h/l   stack into the column to the left/right
#   Alt+m j/k   sit beside the pane below/above, turning a stack into a row
#
# Nothing happens at the window edge, because there is no neighbour there.
# The key table reverts to root after one key, so this is a single chord,
# not a mode that has to be left.

set -s command-alias[104] "tile-merge-left=select-pane -M ; \
if -F '#{window_zoomed_flag}' { resize-pane -Z } ; \
if -F '#{==:#{pane_at_left},0}' { \
	if -F '#{pane_at_bottom}' { \
		join-pane -v -t '{left-of}' ; select-layout -E \
	} { \
		join-pane -v -b -t '{left-of}' ; select-layout -E \
	} \
}"

set -s command-alias[105] "tile-merge-right=select-pane -M ; \
if -F '#{window_zoomed_flag}' { resize-pane -Z } ; \
if -F '#{==:#{pane_at_right},0}' { \
	if -F '#{pane_at_bottom}' { \
		join-pane -v -t '{right-of}' ; select-layout -E \
	} { \
		join-pane -v -b -t '{right-of}' ; select-layout -E \
	} \
}"

set -s command-alias[106] "tile-merge-up=select-pane -M ; \
if -F '#{window_zoomed_flag}' { resize-pane -Z } ; \
if -F '#{==:#{pane_at_top},0}' { \
	if -F '#{pane_at_right}' { \
		join-pane -h -t '{up-of}' ; select-layout -E \
	} { \
		join-pane -h -b -t '{up-of}' ; select-layout -E \
	} \
}"

set -s command-alias[107] "tile-merge-down=select-pane -M ; \
if -F '#{window_zoomed_flag}' { resize-pane -Z } ; \
if -F '#{==:#{pane_at_bottom},0}' { \
	if -F '#{pane_at_right}' { \
		join-pane -h -t '{down-of}' ; select-layout -E \
	} { \
		join-pane -h -b -t '{down-of}' ; select-layout -E \
	} \
}"

bind -n M-m switch-client -T merge

bind -T merge h tile-merge-left
bind -T merge j tile-merge-down
bind -T merge k tile-merge-up
bind -T merge l tile-merge-right

bind -T merge Left  tile-merge-left
bind -T merge Down  tile-merge-down
bind -T merge Up    tile-merge-up
bind -T merge Right tile-merge-right

bind -T merge Enter  switch-client -T root
bind -T merge Escape switch-client -T root


##### Create panes / layout #################################################

# Alt+Enter: new pane, split along the longer side of the current pane.
# Terminal cells are about twice as tall as they are wide, hence the *2.
bind -n M-Enter if -F '#{e|>:#{pane_width},#{e|*:#{pane_height},2}}' {
	split-window -h -c '#{pane_current_path}'
} {
	split-window -v -c '#{pane_current_path}'
}

# Explicit split orientation.
bind -n M-b split-window -h -c '#{pane_current_path}'
bind -n M-v split-window -v -c '#{pane_current_path}'

bind -n M-e next-layout
bind -n M-f resize-pane -Z

# Shift+q arrives as Q.
bind -n M-Q kill-pane


##### Resize mode: Alt+r, then hjkl OR arrows ###############################
#
# The mode stays active until Enter or Escape. Any other key leaves it too,
# because unbound keys fall back to the root table. status-right names the
# key table whenever it is not root, so the mode is visible.

bind -n M-r switch-client -T resize

bind -T resize h resize-pane -L 5 \; switch-client -T resize
bind -T resize j resize-pane -D 2 \; switch-client -T resize
bind -T resize k resize-pane -U 2 \; switch-client -T resize
bind -T resize l resize-pane -R 5 \; switch-client -T resize

bind -T resize Left  resize-pane -L 5 \; switch-client -T resize
bind -T resize Down  resize-pane -D 2 \; switch-client -T resize
bind -T resize Up    resize-pane -U 2 \; switch-client -T resize
bind -T resize Right resize-pane -R 5 \; switch-client -T resize

# Give the panes around this one equal shares, without leaving the mode.
bind -T resize = select-layout -E \; switch-client -T resize

bind -T resize Enter  switch-client -T root
bind -T resize Escape switch-client -T root


##### Workspaces ############################################################
#
# ":N" means window N in the current session. Alt+0 is workspace 10, so the
# workspaces read 1..10 in order. list-panes is only a probe for "does this
# window exist", so its output and its error are both discarded. It runs
# the tmux binary, so tmux has to be on PATH in the server environment;
# without it, selecting a workspace that exists fails with "index in use".
# Command aliases cannot help here: tmux does not expand formats in -t.

bind -n M-1 if-shell 'tmux list-panes -t :1 >/dev/null 2>&1' { select-window -t :1 } { new-window -t :1 -c '#{pane_current_path}' }
bind -n M-2 if-shell 'tmux list-panes -t :2 >/dev/null 2>&1' { select-window -t :2 } { new-window -t :2 -c '#{pane_current_path}' }
bind -n M-3 if-shell 'tmux list-panes -t :3 >/dev/null 2>&1' { select-window -t :3 } { new-window -t :3 -c '#{pane_current_path}' }
bind -n M-4 if-shell 'tmux list-panes -t :4 >/dev/null 2>&1' { select-window -t :4 } { new-window -t :4 -c '#{pane_current_path}' }
bind -n M-5 if-shell 'tmux list-panes -t :5 >/dev/null 2>&1' { select-window -t :5 } { new-window -t :5 -c '#{pane_current_path}' }
bind -n M-6 if-shell 'tmux list-panes -t :6 >/dev/null 2>&1' { select-window -t :6 } { new-window -t :6 -c '#{pane_current_path}' }
bind -n M-7 if-shell 'tmux list-panes -t :7 >/dev/null 2>&1' { select-window -t :7 } { new-window -t :7 -c '#{pane_current_path}' }
bind -n M-8 if-shell 'tmux list-panes -t :8 >/dev/null 2>&1' { select-window -t :8 } { new-window -t :8 -c '#{pane_current_path}' }
bind -n M-9 if-shell 'tmux list-panes -t :9 >/dev/null 2>&1' { select-window -t :9 } { new-window -t :9 -c '#{pane_current_path}' }
bind -n M-0 if-shell 'tmux list-panes -t :10 >/dev/null 2>&1' { select-window -t :10 } { new-window -t :10 -c '#{pane_current_path}' }

bind -n C-M-Left  previous-window
bind -n C-M-Right next-window

# Back to the workspace used before this one. Alt+backtick is there because
# desktops that are not i3 tend to swallow Alt+Tab before the terminal sees
# it.
bind -n M-Tab last-window
bind -n 'M-`' last-window

# %%% substitutes the answer with " \ $ ; ~ escaped, so a name cannot end
# the command and start another one, and -- keeps a leading dash a name.
# Two costs: a backslash in a name arrives doubled, and tmux expands #{}
# and #() in the name itself, which no quoting here can prevent.
bind -n M-n command-prompt -p 'rename workspace:' 'rename-window -- "%%%"'


##### Alt+Shift+number = move pane to workspace #############################
#
# Shifted number encoding:
#   1 !   2 @   3 #   4 $   5 %   6 ^   7 &   8 *   9 (   0 )
#
# Behaviour:
#   - if the destination exists: join the pane there with -d, so this
#     workspace stays selected and focus falls to a pane that remains here;
#   - if it does not exist and this window has other panes: break the pane
#     into window N with -d, again staying here;
#   - if this is the only pane in the window, the whole window has to move,
#     because no pane would be left here to stay focused on. That does
#     follow the window to workspace N.

bind -n 'M-!' if -F '#{!=:#{window_index},1}' {
	if-shell 'tmux list-panes -t :1 >/dev/null 2>&1' { select-pane -M ; join-pane -d -h -t :1 } {
		if -F '#{==:#{window_panes},1}' { move-window -t :1 } { break-pane -d -t :1 }
	}
}
bind -n 'M-@' if -F '#{!=:#{window_index},2}' {
	if-shell 'tmux list-panes -t :2 >/dev/null 2>&1' { select-pane -M ; join-pane -d -h -t :2 } {
		if -F '#{==:#{window_panes},1}' { move-window -t :2 } { break-pane -d -t :2 }
	}
}
bind -n 'M-#' if -F '#{!=:#{window_index},3}' {
	if-shell 'tmux list-panes -t :3 >/dev/null 2>&1' { select-pane -M ; join-pane -d -h -t :3 } {
		if -F '#{==:#{window_panes},1}' { move-window -t :3 } { break-pane -d -t :3 }
	}
}
bind -n 'M-$' if -F '#{!=:#{window_index},4}' {
	if-shell 'tmux list-panes -t :4 >/dev/null 2>&1' { select-pane -M ; join-pane -d -h -t :4 } {
		if -F '#{==:#{window_panes},1}' { move-window -t :4 } { break-pane -d -t :4 }
	}
}
bind -n 'M-%' if -F '#{!=:#{window_index},5}' {
	if-shell 'tmux list-panes -t :5 >/dev/null 2>&1' { select-pane -M ; join-pane -d -h -t :5 } {
		if -F '#{==:#{window_panes},1}' { move-window -t :5 } { break-pane -d -t :5 }
	}
}
bind -n 'M-^' if -F '#{!=:#{window_index},6}' {
	if-shell 'tmux list-panes -t :6 >/dev/null 2>&1' { select-pane -M ; join-pane -d -h -t :6 } {
		if -F '#{==:#{window_panes},1}' { move-window -t :6 } { break-pane -d -t :6 }
	}
}
bind -n 'M-&' if -F '#{!=:#{window_index},7}' {
	if-shell 'tmux list-panes -t :7 >/dev/null 2>&1' { select-pane -M ; join-pane -d -h -t :7 } {
		if -F '#{==:#{window_panes},1}' { move-window -t :7 } { break-pane -d -t :7 }
	}
}
bind -n 'M-*' if -F '#{!=:#{window_index},8}' {
	if-shell 'tmux list-panes -t :8 >/dev/null 2>&1' { select-pane -M ; join-pane -d -h -t :8 } {
		if -F '#{==:#{window_panes},1}' { move-window -t :8 } { break-pane -d -t :8 }
	}
}
bind -n 'M-(' if -F '#{!=:#{window_index},9}' {
	if-shell 'tmux list-panes -t :9 >/dev/null 2>&1' { select-pane -M ; join-pane -d -h -t :9 } {
		if -F '#{==:#{window_panes},1}' { move-window -t :9 } { break-pane -d -t :9 }
	}
}
bind -n 'M-)' if -F '#{!=:#{window_index},10}' {
	if-shell 'tmux list-panes -t :10 >/dev/null 2>&1' { select-pane -M ; join-pane -d -h -t :10 } {
		if -F '#{==:#{window_panes},1}' { move-window -t :10 } { break-pane -d -t :10 }
	}
}


##### Status bar ############################################################
# %Y etc are expanded by tmux itself, so the status line forks nothing.

set -g status-left '[#S] '
set -g status-right '#{?#{==:#{client_key_table},root},,[#{client_key_table}] }%Y-%m-%d %H:%M'
set -g window-status-format ' #I:#W '
set -g window-status-current-format '[#I:#W#{?window_zoomed_flag, Z,}]'