# http://rust-lang.org
# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾

# Detection
# ‾‾‾‾‾‾‾‾‾

hook global BufCreate .*[.](rust|rs) %{
    set-option buffer filetype rust
}

# Initialization
# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾

hook global WinSetOption filetype=rust %[
    require-module rust
    hook window ModeChange pop:insert:.* -group rust-trim-indent rust-trim-indent
    hook window InsertChar \n -group rust-indent rust-indent-on-new-line
    hook window InsertChar \{ -group rust-indent rust-indent-on-opening-curly-brace
    hook window InsertChar [)}] -group rust-indent rust-indent-on-closing
    hook -once -always window WinSetOption filetype=.* %{ remove-hooks window rust-.+ }
]

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

provide-module rust %§

# Highlighters
# ‾‾‾‾‾‾‾‾‾‾‾‾

add-highlighter shared/rust regions
add-highlighter shared/rust/code default-region group
add-highlighter shared/rust/string           region %{(?<!')"} (?<!\\)(\\\\)*"              fill string
add-highlighter shared/rust/raw_string       region -match-capture %{(?<!')r(#*)"} %{"(#*)} fill string

add-highlighter shared/rust/line_doctest region ^\h*//[!/]\h*```($|should_panic|no_run|ignore|allow_fail|rust|test_harness|compile_fail|E\d{4}|edition201[58]) ^\h*//[!/]\h*```$ regions
add-highlighter shared/rust/line_doctest/marker region ```.* $ group
add-highlighter shared/rust/line_doctest/marker/fence regex ``` 0:meta
add-highlighter shared/rust/line_doctest/marker/keywords regex [\d\w] 0:meta # already matched above, just ignore comma
add-highlighter shared/rust/line_doctest/inner region '^\h*//[!/]( #(?= )|)' '$| ' group
add-highlighter shared/rust/line_doctest/inner/comment regex //[!/] 0:documentation
add-highlighter shared/rust/line_doctest/inner/hidden regex '#' 0:meta
add-highlighter shared/rust/line_doctest/code default-region ref rust
add-highlighter shared/rust/line_code_rest   region ^\h*//[!/]\h*``` ^\h*//[!/]\h*```$      fill documentation # reset invalid doctest
add-highlighter shared/rust/line_comment2    region //[!/]{2} $                             fill comment
add-highlighter shared/rust/line_doc         region //[!/] $                                fill documentation
add-highlighter shared/rust/line_comment1    region // $                                    fill comment

add-highlighter shared/rust/block_comment2   region -recurse /\*\*\* /\*\*\* \*/            fill comment
add-highlighter shared/rust/block_doc        region -recurse /\*\* /\*\* \*/ regions
add-highlighter shared/rust/block_doc/doctest region ```($|should_panic|no_run|ignore|allow_fail|rust|test_harness|compile_fail|E\d{4}|edition201[58]) ```$ regions
add-highlighter shared/rust/block_doc/doctest/marker region ```.* $ group
add-highlighter shared/rust/block_doc/doctest/marker/fence regex ``` 0:meta
add-highlighter shared/rust/block_doc/doctest/marker/keywords regex [\d\w] 0:meta # already matched above, just ignore comma
add-highlighter shared/rust/block_doc/doctest/inner default-region group
add-highlighter shared/rust/block_doc/doctest/inner/hidden regex '^\h*\**\h*#' 0:meta
add-highlighter shared/rust/block_doc/doctest/inner/comment regex ^\h*\* 0:documentation
add-highlighter shared/rust/block_doc/doctest/inner/code ref rust
add-highlighter shared/rust/block_doc/code_rest region ``` ``` fill documentation
add-highlighter shared/rust/block_doc/doc    default-region fill documentation
add-highlighter shared/rust/block_comment1   region -recurse /\* /\* \*/                    fill comment

add-highlighter shared/rust/macro_attributes region -recurse "\[" "#!?\[" "\]" regions
add-highlighter shared/rust/macro_attributes/ default-region fill meta
add-highlighter shared/rust/macro_attributes/string region %{(?<!')"} (?<!\\)(\\\\)*" fill string
add-highlighter shared/rust/macro_attributes/raw_string region -match-capture %{(?<!')r(#*)"} %{"(#*)} fill string

add-highlighter shared/rust/code/long_quoted          regex "('\w+)[^']" 1:meta
add-highlighter shared/rust/code/field_or_parameter   regex (_?\w+)(?::)(?!:) 1:variable
add-highlighter shared/rust/code/namespace            regex [a-zA-Z](\w+)?(\h+)?(?=::) 0:module
add-highlighter shared/rust/code/field                regex ((?<!\.\.)(?<=\.))_?[a-zA-Z]\w*\b 0:meta
add-highlighter shared/rust/code/function_call        regex _?[a-zA-Z]\w*\s*(?=\() 0:function
add-highlighter shared/rust/code/user_defined_type    regex \b[A-Z]\w*\b 0:type
add-highlighter shared/rust/code/function_declaration regex (?:fn\h+)(_?\w+)(?:<[^>]+?>)?\( 1:function
add-highlighter shared/rust/code/variable_declaration regex (?:let\h+(?:mut\h+)?)(_?\w+) 1:variable
add-highlighter shared/rust/code/macro                regex \b[A-z0-9_]+! 0:meta
# the number literals syntax is defined here:
# https://doc.rust-lang.org/reference/tokens.html#numbers
add-highlighter shared/rust/code/values regex \b(?:self|true|false|[0-9][_0-9]*(?:\.[0-9][_0-9]*|(?:\.[0-9][_0-9]*)?E[\+\-][_0-9]+)(?:f(?:32|64))?|(?:0x[_0-9a-fA-F]+|0o[_0-7]+|0b[_01]+|[0-9][_0-9]*)(?:(?:i|u|f)(?:8|16|32|64|128|size))?)\b 0:value
add-highlighter shared/rust/code/attributes regex \b(?:trait|struct|enum|union|type|mut|ref|static|const|default)\b 0:attribute
# the language keywords are defined here, but many of them are reserved and unused yet:
# https://doc.rust-lang.org/reference/keywords.html
add-highlighter shared/rust/code/keywords             regex \b(?:let|as|fn|return|match|if|else|loop|for|in|while|break|continue|move|box|where|impl|dyn|pub|unsafe|async|await|mod|crate|use|extern)\b 0:keyword
add-highlighter shared/rust/code/char_character       regex "'([^\\]|\\(.|x[0-9a-fA-F]{2}|u\{[0-9a-fA-F]{1,6}\}))'" 0:green
# TODO highlight error for unicode or single escape byte character
add-highlighter shared/rust/code/byte_character       regex b'([\x00-\x5B\x5D-\x7F]|\\(.|x[0-9a-fA-F]{2}))' 0:yellow
add-highlighter shared/rust/code/builtin_types        regex \b(?:u8|u16|u32|u64|u128|usize|i8|i16|i32|i64|i128|isize|f32|f64|bool|char|str|Self)\b 0:type
add-highlighter shared/rust/code/return               regex \breturn\b 0:meta

# Commands
# ‾‾‾‾‾‾‾‾

define-command -hidden rust-trim-indent %{
    # remove trailing white spaces
    try %{ execute-keys -draft -itersel <a-x> s \h+$ <ret> d }
}

define-command -hidden rust-indent-on-new-line %~
    evaluate-commands -draft -itersel %<
        try %{
            try %[ # line comment
                evaluate-commands -draft -save-regs '/"' %[
                    # copy the commenting prefix
                    execute-keys -save-regs '' k <a-x> s ^\h*//[!/]{0,2}\h* <ret> y
                    try %[
                        # if the previous comment isn't empty, create a new one
                        execute-keys <a-x><a-K>^\h*//[!/]{0,2}$<ret> j<a-x>s^\h*<ret>P
                    ] catch %[
                        # TODO figure out a way to not delete empty comment in current line
                        # if there is no space and text in the previous comment, remove it completely
                        execute-keys s //.*<ret> d
                    ]
                ]
            ] catch %[ # block comment
                # if the previous line isn't within a comment scope, break
                execute-keys -draft k<a-x> <a-k>^(\h*/\*|\h+\*(?!/))<ret>

                # find comment opening, validate it was not closed, and check its using star prefixes
                execute-keys -draft <a-?>/\*<ret><a-H> <a-K>\*/<ret> <a-k>\A\h*/\*([^\n]*\n\h*\*)*[^\n]*\n\h*.\z<ret>

                try %[
                    # if the previous line is opening the comment, insert star preceeded by space
                    execute-keys -draft k<a-x><a-k>^\h*/\*<ret>
                    execute-keys -draft i*<space><esc>
                ] catch %[
                    try %[
                        # if the next line is a comment line insert a star
                        execute-keys -draft j<a-x><a-k>^\h+\*<ret>
                        execute-keys -draft i*<space><esc>
                    ] catch %[
                        try %[
                            # if the previous line is an empty comment line, close the comment scope
                            execute-keys -draft k<a-x><a-k>^\h+\*\h+$<ret> <a-x>1s\*(\h*)<ret>c/<esc>
                        ] catch %[
                            # if the previous line is a non-empty comment line, add a star
                            execute-keys -draft i*<space><esc>
                        ]
                    ]
                ]

                # trim trailing whitespace on the previous line
                try %[ execute-keys -draft s\h+$<ret> d ]
                # align the new star with the previous one
                execute-keys K<a-x>1s^[^*]*(\*)<ret>&
            ]
        } catch %`
            # preserve previous line indent
            try %{ execute-keys -draft <semicolon> K <a-&> }
            # indent after lines ending with { or (
            try %[ execute-keys -draft k <a-x> <a-k> [{(]\h*$ <ret> j <a-gt> ]
            # indent after lines ending with [{(].+ and move first parameter to own line
            try %< execute-keys -draft [c[({],[)}] <ret> <a-k> \A[({][^\n]+\n[^\n]*\n?\z <ret> L i<ret><esc> <gt> <a-S> <a-&> >
            # indent lines with a standalone where
            try %+ execute-keys -draft k <a-x> <a-k> ^\h*where\h*$ <ret> j <a-gt> +
            # dedent after lines starting with . and ending with , or ;
            try %_ execute-keys -draft k <a-x> <a-k> ^\h*\..*[,<semicolon>]\h*$ <ret> j <a-lt> _
            # deindent closing brace(s) when after cursor
            try %= execute-keys -draft <a-x> <a-k> ^\h*[})] <ret> gh / [})] <ret> m <a-S> 1<a-&> =
            # todo dedent additional unmatched parenthesis
            # try %& execute-keys -draft k <a-x> s \((?:[^)(]+|\((?:[^)(]+|\([^)(]*\))*\))*\) l Gl s\) %sh{
                # count previous selections length
                # printf "j $(echo $kak_selections_length | wc -w) <a-lt>"
            # } &
        `
        # filter previous line
        try %{ execute-keys -draft k : rust-trim-indent <ret> }
    >
~

define-command -hidden rust-indent-on-opening-curly-brace %[
    evaluate-commands -draft -itersel %_
        # align indent with opening paren when { is entered on a new line after the closing paren
        try %[ execute-keys -draft h <a-F> ) M <a-k> \A\(.*\)\h*\n\h*\{\z <ret> s \A|.\z <ret> 1<a-&> ]
        # dedent standalone { after impl and related block without any { in between
        try %< execute-keys -draft hh <a-?> impl|fn|struct|enum|union|if|for <ret> <a-K> \{ <ret> <a-semicolon> <semicolon> ll <a-x> <a-k> ^\h*\{$ <ret> <a-lt> >
    _
]

define-command -hidden rust-indent-on-closing %[
    evaluate-commands -draft -itersel %_
        # align to opening curly brace or paren when alone on a line
        try %< execute-keys -draft <a-h> <a-k> ^\h*[)}]$ <ret> h m <a-S> 1<a-&> >
    _
]

§