# https://golang.org/
#

# Detection
# ‾‾‾‾‾‾‾‾‾

hook global BufCreate .*\.go %{
    set-option buffer filetype go
}

# Initialization
# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾

hook global WinSetOption filetype=go %{
    require-module go

    set-option window static_words %opt{go_static_words}

    # cleanup trailing whitespaces when exiting insert mode
    hook window ModeChange insert:.* -group go-trim-indent %{ try %{ execute-keys -draft <a-x>s^\h+$<ret>d } }
    hook window InsertChar \n -group go-indent go-indent-on-new-line
    hook window InsertChar \{ -group go-indent go-indent-on-opening-curly-brace
    hook window InsertChar \} -group go-indent go-indent-on-closing-curly-brace

    hook -once -always window WinSetOption filetype=.* %{ remove-hooks window go-.+ }
}

hook -group go-highlight global WinSetOption filetype=go %{
    add-highlighter window/go ref go
    hook -once -always window WinSetOption filetype=.* %{ remove-highlighter window/go }
}

provide-module go %🦀

# Highlighters
# ‾‾‾‾‾‾‾‾‾‾‾‾

add-highlighter shared/go regions
add-highlighter shared/go/code default-region group
add-highlighter shared/go/back_string region '`' '`' fill string
add-highlighter shared/go/double_string region '"' (?<!\\)(\\\\)*" fill string
add-highlighter shared/go/single_string region "'" (?<!\\)(\\\\)*' fill string
add-highlighter shared/go/comment region /\* \*/ fill comment
add-highlighter shared/go/comment_line region '//' $ fill comment

add-highlighter shared/go/code/ regex %{-?([0-9]*\.(?!0[xX]))?\b([0-9]+|0[xX][0-9a-fA-F]+)\.?([eE][+-]?[0-9]+)?i?\b} 0:value

evaluate-commands %sh{
    # Grammar
    keywords='break default func interface select case defer go map struct
              chan else goto package switch const fallthrough if range type
              continue for import return var'
    types='bool byte chan complex128 complex64 error float32 float64 int int16 int32
           int64 int8 interface intptr map rune string struct uint uint16 uint32 uint64 uint8'
    values='false true nil iota'
    functions='append cap close complex copy delete imag len make new panic print println real recover'

    join() { sep=$2; eval set -- $1; IFS="$sep"; echo "$*"; }

    # Add the language's grammar to the static completion list
    printf %s\\n "declare-option str-list go_static_words $(join "${keywords} ${attributes} ${types} ${values} ${functions}" ' ')"

    # Highlight keywords
    printf %s "
        add-highlighter shared/go/code/ regex \b($(join "${keywords}" '|'))\b 0:keyword
        add-highlighter shared/go/code/ regex \b($(join "${attributes}" '|'))\b 0:attribute
        add-highlighter shared/go/code/ regex \b($(join "${types}" '|'))\b 0:type
        add-highlighter shared/go/code/ regex \b($(join "${values}" '|'))\b 0:value
        add-highlighter shared/go/code/ regex \b($(join "${functions}" '|'))\b 0:builtin
    "
}

# Commands
# ‾‾‾‾‾‾‾‾

define-command -hidden go-indent-on-new-line %~
    evaluate-commands -draft -itersel %=
        # preserve previous line indent
        try %{ execute-keys -draft \;K<a-&> }
        # indent after lines ending with { or (
        try %[ execute-keys -draft k<a-x> <a-k> [{(]\h*$ <ret> j<a-gt> ]
        # cleanup trailing white spaces on the previous line
        try %{ execute-keys -draft k<a-x> s \h+$ <ret>d }
        # align to opening paren of previous line
        try %{ execute-keys -draft [( <a-k> \A\([^\n]+\n[^\n]*\n?\z <ret> s \A\(\h*.|.\z <ret> '<a-;>' & }
        # copy // comments prefix
        try %{ execute-keys -draft \;<c-s>k<a-x> s ^\h*\K/{2,} <ret> y<c-o>P<esc> }
        # indent after a switch's case/default statements
        try %[ execute-keys -draft k<a-x> <a-k> ^\h*(case|default).*:$ <ret> j<a-gt> ]
        # indent after if|else|while|for
        try %[ execute-keys -draft \;<a-F>)MB <a-k> \A(if|else|while|for)\h*\(.*\)\h*\n\h*\n?\z <ret> s \A|.\z <ret> 1<a-&>1<a-space><a-gt> ]
    =
~

define-command -hidden go-indent-on-opening-curly-brace %[
    # align indent with opening paren when { is entered on a new line after the closing paren
    try %[ execute-keys -draft -itersel h<a-F>)M <a-k> \A\(.*\)\h*\n\h*\{\z <ret> s \A|.\z <ret> 1<a-&> ]
]

define-command -hidden go-indent-on-closing-curly-brace %[
    # align to opening curly brace when alone on a line
    try %[ execute-keys -itersel -draft <a-h><a-k>^\h+\}$<ret>hms\A|.\z<ret>1<a-&> ]
]

🦀