# Detection
# ‾‾‾‾‾‾‾‾‾

hook global BufSetOption mimetype=text/x-javascript %{
    set buffer filetype javascript
}

hook global BufCreate .*[.](js) %{
    set buffer filetype javascript
}

# Highlighters
# ‾‾‾‾‾‾‾‾‾‾‾‾

addhl -group / regions -default code javascript \
    double_string '"' (?<!\\)(\\\\)*"        '' \
    single_string "'" "'"                    '' \
    comment       //  '$'                    '' \
    comment      /[*] [*]/                   '' \
    regex         /   (?<!\\)(\\\\)*/[gimy]* ''

# Regular expression flags are: g → global match, i → ignore case, m → multi-lines, y → sticky
# https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp

addhl -group /javascript/double_string fill string
addhl -group /javascript/single_string fill string
addhl -group /javascript/regex         fill meta
addhl -group /javascript/comment       fill comment

addhl -group /javascript/code regex \$\w* 0:identifier
addhl -group /javascript/code regex \<(document|false|null|parent|self|this|true|undefined|window)\> 0:value
addhl -group /javascript/code regex \<(Array|Boolean|Date|Function|Number|Object|RegExp|String)\> 0:type

# Keywords are collected at
# https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#Keywords
addhl -group /javascript/code regex \<(break|case|catch|class|const|continue|debugger|default|delete|do|else|export|extends|finally|for|function|if|import|in|instanceof|let|new|return|super|switch|throw|try|typeof|var|void|while|with|yield)\> 0:keyword

# Commands
# ‾‾‾‾‾‾‾‾

def -hidden _javascript_filter_around_selections %{
    eval -draft -itersel %{
        exec <a-x>
        # remove trailing white spaces
        try %{ exec -draft s \h+$ <ret> d }
    }
}

def -hidden _javascript_indent_on_char "
    eval -draft -itersel '
        # indent closer token to its opener
        try %_ exec -draft gh <a-k> ^\h*[]}] <ret> m <a-&> _
    '
"

def -hidden _javascript_indent_on_new_line "
    eval -draft -itersel '
        # preserve previous line indent
        try %{ exec -draft <space> K <a-&> }
        # filter previous line
        try %{ exec -draft k : _javascript_filter_around_selections <ret> }
        # copy // comments prefix and following white spaces
        try %{ exec -draft k x s ^\h*\K#\h* <ret> y j p }
        # indent after lines beginning / ending with opener token
        try %_ exec -draft k x <a-k> ^\h*[[{]|[[{]$ <ret> j <a-gt> _
    '
"

# Initialization
# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾

hook global WinSetOption filetype=javascript %{
    addhl ref javascript

    hook window InsertEnd  .* -group javascript-hooks  _javascript_filter_around_selections
    hook window InsertChar .* -group javascript-indent _javascript_indent_on_char
    hook window InsertChar \n -group javascript-indent _javascript_indent_on_new_line
}

hook global WinSetOption filetype=(?!javascript).* %{
    rmhl javascript
    rmhooks window javascript-indent
    rmhooks window javascript-hooks
}