--
-- vis-commentary
--
-- comment strings and matching patterns are taken from:
-- https://github.com/rgieseke/textadept/blob/9906c1fcec1c33c6a83c33dc7874669b5c6113f8/modules/textadept/editing.lua
--

local comment_string = {
    actionscript='//', ada='--', ansi_c='/*|*/', antlr='//', apdl='!', apl='#',
    applescript='--', asp='\'', autoit=';', awk='#', b_lang='//', bash='#',
    batch=':', bibtex='%', boo='#', chuck='//', cmake='#', coffeescript='#',
    context='%', cpp='//', crystal='#', csharp='//', css='/*|*/', cuda='//',
    dart='//', desktop='#', django='{#|#}', dmd='//', dockerfile='#', dot='//',
    eiffel='--', elixir='#', erlang='%', faust='//', fish='#', forth='|\\',
    fortran='!', fsharp='//', gap='#', gettext='#', gherkin='#', glsl='//',
    gnuplot='#', go='//', groovy='//', gtkrc='#', haskell='--', html='<!--|-->',
    icon='#', idl='//', inform='!', ini='#', Io='#', java='//', javascript='//',
    json='/*|*/', jsp='//', latex='%', ledger='#', less='//', lilypond='%',
    lisp=';', logtalk='%', lua='--', makefile='#', markdown='<!--|-->', matlab='#', 
    moonscript='--', myrddin='//', nemerle='//', nsis='#', objective_c='//', 
    pascal='//', perl='#', php='//', pico8='//', pike='//', pkgbuild='#', prolog='%',
    props='#', protobuf='//', ps='%', pure='//', python='#', rails='#', rc='#',
    rebol=';', rest='.. ', rexx='--', rhtml='<!--|-->', rstats='#', ruby='#',
    rust='//', sass='//', scala='//', scheme=';', smalltalk='"|"', sml='(*)',
    snobol4='#', sql='#', tcl='#', tex='%', text='', toml='#', vala='//',
    vb='\'', vbscript='\'', verilog='//', vhdl='--', wsf='<!--|-->',
    xml='<!--|-->', yaml='#'
}

-- escape all magic characters with a '%'
local function esc(str)
    if not str then return "" end
    return (str:gsub('%%', '%%%%')
        :gsub('^%^', '%%^')
        :gsub('%$$', '%%$')
        :gsub('%(', '%%(')
        :gsub('%)', '%%)')
        :gsub('%.', '%%.')
        :gsub('%[', '%%[')
        :gsub('%]', '%%]')
        :gsub('%*', '%%*')
        :gsub('%+', '%%+')
        :gsub('%-', '%%-')
        :gsub('%?', '%%?'))
end

-- escape '%'
local function pesc(str)
    if not str then return "" end
    return str:gsub('%%', '%%%%')
end

function rtrim(s)
    local n = #s
    while n > 0 and s:find("^%s", n) do n = n - 1 end
    return s:sub(1, n)
 end

local function comment_line(lines, lnum, prefix, suffix)
    if suffix ~= "" then suffix = " " .. suffix end
    lines[lnum] = string.gsub(lines[lnum],
                              "(%s*)(.*)",
                              "%1" .. pesc(prefix) .. " %2" .. pesc(suffix))
end

local function uncomment_line(lines, lnum, prefix, suffix)
    local match_str = "^(%s*)" .. esc(prefix) .. "%s?(.*)" .. esc(suffix)
    m = table.pack(lines[lnum]:match(match_str))
    lines[lnum] = m[1] .. rtrim(m[2])
end

local function is_comment(line, prefix)
    return (line:match("^%s*(.+)"):sub(0, #prefix) == prefix)
end

local function toggle_line_comment(lines, lnum, prefix, suffix)
    if not lines or not lines[lnum] then return end
    if not lines[lnum]:match("^%s*(.+)") then return end -- ignore empty lines
    if is_comment(lines[lnum], prefix) then
        uncomment_line(lines, lnum, prefix, suffix)
    else
        comment_line(lines, lnum, prefix, suffix)
    end
end

-- if one line inside the block is not a comment, comment the block.
-- only uncomment, if every single line is comment.
local function block_comment(lines, a, b, prefix, suffix)
    local uncomment = true
    for i=a,b do
        if lines[i]:match("^%s*(.+)") and not is_comment(lines[i], prefix) then
            uncomment = false
        end
    end

    if uncomment then
        for i=a,b do
            if lines[i]:match("^%s*(.+)") then
                uncomment_line(lines, i, prefix, suffix)
            end
        end
    else
        for i=a,b do
            if lines[i]:match("^%s*(.+)") then
                comment_line(lines, i, prefix, suffix)
            end
        end
    end
end

vis:map(vis.modes.NORMAL, "gcc", function()
    local win = vis.win
    local lines = win.file.lines
    local comment = comment_string[win.syntax]
    if not comment then return end
    local prefix, suffix = comment:match('^([^|]+)|?([^|]*)$')
    if not prefix then return end

    for sel in win:selections_iterator() do
        local lnum = sel.line
        local col = sel.col

        toggle_line_comment(lines, lnum, prefix, suffix)
        sel:to(lnum, col)  -- restore cursor position
    end

    win:draw()
end, "Toggle comment on a the current line")

local function visual_f(i)
    return function()
        local win = vis.win
        local lines = win.file.lines

        local comment = comment_string[win.syntax]
        if not comment then return end

        local prefix, suffix = comment:match('^([^|]+)|?([^|]*)$')
        if not prefix then return end

        for sel in win:selections_iterator() do
            local r = sel.range
            local lnum = sel.line     -- line number of cursor
            local col = sel.col       -- column of cursor

            if sel.anchored and r then
                sel.pos = r.start
                local a = sel.line
                sel.pos = r.finish
                local b = sel.line - i

                block_comment(lines, a, b, prefix, suffix)

                sel:to(lnum, col)     -- restore cursor position
            end
        end

        win:draw()
        vis.mode = vis.modes.NORMAL     -- go to normal mode
    end
end

vis:map(vis.modes.VISUAL_LINE, "gc", visual_f(1), "Toggle comment on the selected lines")
vis:map(vis.modes.VISUAL, "gc", visual_f(0), "Toggle comment on the selected lines")