# http://lua.org
# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾

# Detection
# ‾‾‾‾‾‾‾‾‾

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

# Initialization
# ‾‾‾‾‾‾‾‾‾‾‾‾‾‾

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

    hook window ModeChange pop:insert:.* -group lua-indent lua-trim-indent
    hook window InsertChar .* -group lua-indent lua-indent-on-char
    hook window InsertChar \n -group lua-indent lua-indent-on-new-line
    hook window InsertChar \n -group lua-insert lua-insert-on-new-line

    alias window alt lua-alternative-file

    hook -once -always window WinSetOption filetype=.* %{
        remove-hooks window lua-.+
        unalias window alt lua-alternative-file
    }
}

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


provide-module lua %[

# Highlighters
# ‾‾‾‾‾‾‾‾‾‾‾‾

add-highlighter shared/lua regions
add-highlighter shared/lua/code default-region group
add-highlighter shared/lua/raw_string  region -match-capture '\[(=*)\['   '\](=*)\]'       fill string
add-highlighter shared/lua/raw_comment region -match-capture '--\[(=*)\[' '\](=*)\]'       fill comment
add-highlighter shared/lua/double_string region '"'   (?<!\\)(?:\\\\)*" fill string
add-highlighter shared/lua/single_string region "'"   (?<!\\)(?:\\\\)*' fill string
add-highlighter shared/lua/comment       region '--'  $                 fill comment

add-highlighter shared/lua/code/keyword regex \b(and|break|do|else|elseif|end|for|function|goto|if|in|not|or|repeat|return|then|until|while)\b 0:keyword
add-highlighter shared/lua/code/value regex \b(false|nil|true|[0-9]+(:?\.[0-9])?(:?[eE]-?[0-9]+)?|0x[0-9a-fA-F])\b 0:value
add-highlighter shared/lua/code/operator regex (\+|-|\*|/|%|\^|==?|~=|<=?|>=?|\.\.|\.\.\.|#) 0:operator
add-highlighter shared/lua/code/builtin regex \b(_G|_E)\b 0:builtin
add-highlighter shared/lua/code/module regex \b(_G|_E)\b 0:module
add-highlighter shared/lua/code/attribute regex \b(local)\b 0:attribute
add-highlighter shared/lua/code/function_declaration regex \b(?:function\h+)(?:\w+\h*\.\h*)*([a-zA-Z_]\w*)\( 1:function
add-highlighter shared/lua/code/function_call regex \b([a-zA-Z_]\w*)\h*(?=[\(\{]) 1:function

# Commands
# ‾‾‾‾‾‾‾‾

define-command lua-alternative-file -docstring 'Jump to the alternate file (implementation ↔ test)' %{ evaluate-commands %sh{
    case $kak_buffile in
        *spec/*_spec.lua)
            altfile=$(eval printf %s\\n $(printf %s\\n $kak_buffile | sed s+spec/+'*'/+';'s/_spec//))
            [ ! -f $altfile ] && echo "fail 'implementation file not found'" && exit
        ;;
        *.lua)
            path=$kak_buffile
            dirs=$(while [ $path ]; do printf %s\\n $path; path=${path%/*}; done | tail -n +2)
            for dir in $dirs; do
                altdir=$dir/spec
                if [ -d $altdir ]; then
                    altfile=$altdir/$(realpath $kak_buffile --relative-to $dir | sed s+[^/]'*'/++';'s/.lua$/_spec.lua/)
                    break
                fi
            done
            [ ! -d $altdir ] && echo "fail 'spec/ not found'" && exit
        ;;
        *)
            echo "fail 'alternative file not found'" && exit
        ;;
    esac
    printf %s\\n "edit $altfile"
}}

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

define-command -hidden lua-indent-on-char %{
    evaluate-commands -no-hooks -draft -itersel %{
        # align middle and end structures to start and indent when necessary, elseif is already covered by else
        try %{ execute-keys -draft <a-x><a-k>^\h*(else)$<ret><a-semicolon><a-?>^\h*(if)<ret>s\A|.\z<ret>)<a-&> }
        try %{ execute-keys -draft <a-x><a-k>^\h*(end)$<ret><a-semicolon><a-?>^\h*(for|function|if|while)<ret>s\A|.\z<ret>)<a-&> }
    }
}

define-command -hidden lua-indent-on-new-line %{
    evaluate-commands -no-hooks -draft -itersel %{
        # preserve previous non-empty line indent
        try %{ execute-keys -draft <space><a-?>^[^\n]+$<ret>s\A|.\z<ret>)<a-&> }
        # remove trailing white spaces from previous line
        try %{ execute-keys -draft k<a-x>s\h+$<ret>d }
        # indent after start structure
        try %{ execute-keys -draft <a-?>^[^\n]*\w+[^\n]*$<ret><a-k>^\h*(else|elseif|for|function|if|while)\b<ret><a-:><semicolon><a-gt> }
    }
}

define-command -hidden lua-insert-on-new-line %[
    evaluate-commands -no-hooks -draft -itersel %[
        # copy -- comment prefix and following white spaces
        try %{ execute-keys -draft k<a-x>s^\h*\K--\h*<ret>yghjP }
        # wisely add end structure
        evaluate-commands -save-regs x %[
            try %{ execute-keys -draft k<a-x>s^\h+<ret>"xy } catch %{ reg x '' } # Save previous line indent in register x
            try %[ execute-keys -draft k<a-x> <a-k>^<c-r>x(for|function|if|while)<ret> J}iJ<a-x> <a-K>^<c-r>x(else|end|elseif)$<ret> # Validate previous line and that it is not closed yet
                   execute-keys -draft o<c-r>xend<esc> ] # auto insert end
        ]
    ]
]

]