---------------------------------------------------------------------------
-- @author Julien Danjou <julien@danjou.info>
-- @author Sébastien Gross <seb-awesome@chezwam.org>
-- @copyright 2008 Julien Danjou, Sébastien Gross
-- @release @AWESOME_VERSION@
---------------------------------------------------------------------------

-- Grab environment we need
local io = io
local table = table
local math = math
local print = print

--- Completion module for awful
module("awful.completion")

-- mapping of command/completion function
local bashcomp_funcs = {}
local bashcomp_src = "/etc/bash_completion"

--- Enable programmable bash completion in awful.completion.bash at the price of
-- a slight overhead
-- @param src The bash completion source file, /etc/bash_completion by default.
function bashcomp_load(src)
    if src then bashcomp_src = src end
    local c, err = io.popen("/usr/bin/env bash -c 'source " .. bashcomp_src .. "; complete -p'")
    if c then
        while true do
            local line = c:read("*line")
            if not line then break end
            -- if a bash function is used for completion, register it
            if line:match(".* -F .*") then
                bashcomp_funcs[line:gsub(".* (%S+)$","%1")] = line:gsub(".*-F +(%S+) .*$", "%1")
            end
        end
        c:close()
    else
        print(err)
    end
end

local function bash_escape(str)
    res = str:gsub(" ", "\\ ")
    return res
end

--- Use bash completion system to complete command and filename.
-- @param command The command line.
-- @param cur_pos The cursor position.
-- @param ncomp The element number to complete.
-- @return The new command and the new cursor position.
function bash(command, cur_pos, ncomp)
    local wstart = 1
    local wend = 1
    local words = {}
    local cword_index = 0
    local cword_start = 0
    local cword_end = 0
    local i = 1
    local comptype = "file"

    -- do nothing if we are on a letter, i.e. not at len + 1 or on a space
    if cur_pos ~= #command + 1 and command:sub(cur_pos, cur_pos) ~= " " then
        return command, cur_pos
    elseif #command == 0 then
        return command, cur_pos
    end

    while wend <= #command do
        wend = command:find(" ", wstart)
        if not wend then wend = #command + 1 end
        table.insert(words, command:sub(wstart, wend - 1))
        if cur_pos >= wstart and cur_pos <= wend + 1 then
            cword_start = wstart
            cword_end = wend
            cword_index = i
        end
        wstart = wend + 1
        i = i + 1
    end

    if cword_index == 1 then
        comptype = "command"
    end

    local bash_cmd
    if bashcomp_funcs[words[1]] then
        -- fairly complex command with inline bash script to get the possible completions
        bash_cmd = "/usr/bin/env bash -c 'source " .. bashcomp_src .. "; " ..
                   "__print_completions() { for ((i=0;i<${#COMPREPLY[*]};i++)); do echo ${COMPREPLY[i]}; done }; " ..
                   "COMP_WORDS=(" ..  command .."); COMP_LINE=\"" .. command .. "\"; " ..
                   "COMP_COUNT=" .. cur_pos ..  "; COMP_CWORD=" .. cword_index-1 .. "; " ..
                   bashcomp_funcs[words[1]] .. "; __print_completions | sort -u'"
    else
        bash_cmd = "/usr/bin/env bash -c 'compgen -A " .. comptype .. " " .. words[cword_index] .. "'"
    end
    local c, err = io.popen(bash_cmd)
    local output = {}
    i = 0
    if c then
        while true do
            local line = c:read("*line")
            if not line then break end
            table.insert(output, bash_escape(line))
        end

        c:close()
    else
        print(err)
    end

    -- no completion, return
    if #output == 0 then
        return command, cur_pos
    end

    -- cycle
    while ncomp > #output do
        ncomp = ncomp - #output
    end

    local str = command:sub(1, cword_start - 1) .. output[ncomp] .. command:sub(cword_end)
    cur_pos = cword_end + #output[ncomp] + 1

    return str, cur_pos
end

--- Run a generic completion.
-- For this function to run properly the awful.completion.keyword table should
-- be fed up with all keywords. The completion is run against these keywords.
-- @param text The current text the user had typed yet.
-- @param cur_pos The current cursor position.
-- @param ncomp The number of yet requested completion using current text.
-- @param keywords The keywords table uised for completion.
-- @return The new match and the new cursor position.
function generic(text, cur_pos, ncomp, keywords)
    -- The keywords table may be empty
    if #keywords == 0 then
        return text, #text + 1
    end

    -- if no text had been typed yet, then we could start cycling around all
    -- keywords with out filtering and move the cursor at the end of keyword
    if text == nil or #text == 0 then
        ncomp = math.mod(ncomp - 1, #keywords) + 1
        return keywords[ncomp], #keywords[ncomp] + 2
    end

    -- Filter out only keywords starting with text
    local matches = {}
    table.foreach(keywords, function(_, x)
        if x:sub(1 , #text) == text then
            table.insert(matches, x)
        end
    end)

    -- if there are no matches just leave out with the current text and position
    if #matches == 0 then
        return text, #text + 1
    end

    --  cycle around all matches
    ncomp = math.mod(ncomp - 1, #matches) + 1
    return matches[ncomp], #matches[ncomp] + 1
end

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