-- $Id$
-- view.tlu view a document and/or display the list of results in texdoc
--
-- Manuel Pégourié-Gonnard, GPLv3+, see texdoclib.tlu for details

-----------------------------   view a document   -----------------------------

-- view a document
-- see search.tlu for the structure of the argument
function view_doc(docfile)
    return view_file(docfile.realpath)
end

-- get viewer and viewer_replacement before calling try_viewing
-- returns false of failure, true on success
-- viewer_replacement is either:
-- 1. the filename, quoted with "
-- 2. the filename, quoted with " followed by some rm commands
-- The second case happens when the doc was zipped. In the case, this function
-- unzips it in a tempdir so that the viewer command can use the unzipped file.
function view_file (filename)
    local viewer, viewer_replacement
    -- check if the file is zipped
    local nozipname, zipext = parse_zip(filename)
    -- determine viewer_replacement
    if zipext then
        local unzip_cmd = config['unzip_'..zipext]
        if not unzip_cmd then
            err_print('error',
            "No unzip command for ."..zipext..' files, skipping '..filename)
            return false
        end
        local tmpdir = os.tmpdir("/tmp/texdoc.XXXXXX")
        if not tmpdir then
            err_print('error', 'Failed to create tempdir to unzip.')
            return false
        end
        local basename = string.match(nozipname, '.*/(.*)$') or nozipname
        local tmpfile = '"'..tmpdir..'/'..basename..'"'
        local unzip = unzip_cmd..' "'..filename..'">'..tmpfile
        deb_print('view', "Unzip command: "..unzip)
        if not os.execute(unzip) then
            err_print('error', "Failed to unzip '"..filename.."'")
            os.remove(tmpfile)
            os.remove(tmpdir)
            return false
        end
        viewer_replacement = ''..tmpfile..'; '
            ..config.rm_file..' '..tmpfile..'; '
            ..config.rm_dir..' '..tmpdir
        filename = nozipname
    else
        viewer_replacement = '"'..w32_path(filename)..'"'
    end
    -- files without extension are assumed to be text
    local viewext = (filename:match('.*%.([^/]*)$') or 'txt'):lower()
    -- special case : sty files use txt viewer
    if viewext == 'sty' then viewext = 'txt' end
    -- FIXME: hardcoding such cases this way is not very clean
    if viewext == 'texlive' then viewext = 'txt' end
    if viewext == 'htm' then viewext = 'html' end
    -- get a viewer from built-in defaults if not already set
    if not config['viewer_'..viewext] then
        get_default_viewers()
    end
    -- still no viewers? use txt as a fallback
    if not config['viewer_'..viewext] then
        err_print('warning',
            "No viewer_"..viewext.." defined, using viewer_txt.")
        viewext = 'txt'
    end
    assert(config['viewer_'..viewext], 'Internal error: no viewer found.')
    return try_viewing(config['viewer_'..viewext], viewer_replacement)
end

-- view a file, if possible
function try_viewing (view_command, viewer_replacement)
    if string.match (view_command, C.place_holder) then
        view_command = string.gsub(
        view_command, C.place_holder, viewer_replacement)
    else
        view_command = view_command..' '..viewer_replacement
    end

    -- try to catch problems with missing DISPLAY on Unix
    if os.type == 'unix' and not (os.name == 'macosx')
            and os.getenv('DISPLAY') == nil then
        err_print('warning',
        "DISPLAY is not set; your viewer will likely have problems.")
        err_print('warning',
        "Try --list to list results instead of displaying them.")
    end
    err_print('info', 'View command: '..view_command)
     
    -- See long comment below this function for the LC_CTYPE story.
    -- We only want to reset the environment if we have the value
    -- to reset it to. In older versions of luatex, status.lc_* will be nil.
    local env_lc_ctype = status.lc_ctype
    local luatex_lc_ctype = os.setlocale(nil, 'ctype')
    if (env_lc_ctype) then
      err_print('info', "Setting environment LC_CTYPE to: "..env_lc_ctype)
      os.setenv("LC_CTYPE", env_lc_ctype)
    end

    -- the big casino: run the external command.
    if not os.execute(view_command) then
        err_print('error', "Failed to execute: "..view_command)
        return false
    end
    
    -- reset back to "C" (should always be C and always happen, but in case...)
    if (luatex_lc_ctype) then
      os.setenv("LC_CTYPE", luatex_lc_ctype)
    end

    return true
end

-- Explanation of locale madness:
-- LuaTeX resets LC_CTYPE, LC_COLLATE, LC_NUMERIC to "C". That is good for
-- inside luatex, but when we run an external program, if the user's
-- environment is something else, we want to switch back to it. As of
-- TL 2017 LuaTeX, we can inspect the user's locale with status.lc_ctype, etc.
-- 
-- For texdoc purposes, what matters is LC_CTYPE (so we don't bother with
-- the others). For example, with the less pager, when LC_CTYPE=C,
-- non-ASCII bytes are displayed as "<xx>", where xx is the two hex
-- digits for the byte.
-- 
-- See <texdoc-dev-source>/tools/Makefile for a standalone test case.

-----------------------------   display results   -----------------------------

-- print a list of docfile objects (see search.tlu) as a menu
-- if showall is false, stop as soon as a bad result is encountered
function print_menu(name, doclist, showall)
    local max_lines = tonumber(config.max_lines)
    if config.interact_switch and doclist[max_lines+1] then
        -- there may be too many lines, count them
        local n
        if showall then
            n = #doclist
        else
            n = 0
            while doclist[n+1] and doclist[n+1].quality == 'good' do
                n = n + 1
            end
        end
        if n > max_lines then
            io.write (n, " results.  Display them all? (y/N) ")
            local ans = io.read('*line')
            if not ((ans == 'y') or (ans == 'Y')
                -- io.read had a bug wrt windows eol on some versions of texlua
                or (ans == '\ry') or (ans == '\rY')) then
                return
            end
        end
    end
    local i, doc, last_i
    for i, doc in ipairs (doclist) do
        last_i = i -- save for test below
        if doc.quality == 'killed' then break end
        if doc.quality ~= 'good' and not showall then break end
        if config.machine_switch == true then
            print(name, doc.score, w32_path(doc.realpath),
            doc.lang or '', doc.details or '')
        else
            print(string.format('%2d %s', i, w32_path(doc.realpath)))
            if doc.details or doc.lang then
                local line = '   = '
                if doc.lang then line = line..'['..doc.lang..'] ' end
                if doc.details then line = line..doc.details end
                print(line)
            end
        end
    end
    if config.interact_switch then
        io.write ("Enter number of file to view, ",
        "RET to view 1, anything else to skip: ")
        local num_str = io.read('*line')
        -- That returns the empty string on an empty line, nil on EOF.
        -- We only want to default to viewing 1 on an empty line.
        -- Use Lua's faked ternary operator for fun and brevity:
        num = (num_str == "" and 1 or tonumber(num_str))
        if num and doclist[num] and num < last_i then
            view_doc(doclist[num])
        end
    end
end

-----------------------   deliver results based on mode   ---------------------

function deliver_results(name, doclist, many)
    -- ensure that results were found or apologize
    if not doclist[1] or doclist[1].quality == 'killed' then
        if not config.machine_switch then
            local msg = string.gsub(C.notfound_msg, C.notfound_msg_ph, name)
            print(msg) -- get rid of gsub's 2nd value
        end
        return
    end
    -- shall we show all of them or only the "good" ones?
    local showall = (config.mode == 'showall')
    if not showall and doclist[1].quality ~= 'good' then
        showall = true
        err_print('info', 'No good result found, showing all results.')
    end
    -- view result or show menu based on mode and number of results
    if (config.mode == 'view')
        or config.mode == 'mixed' and (not doclist[2]
            or (doclist[2].quality ~= 'good' and not showall)) then
        view_doc(doclist[1])
    else
        if many and not config.machine_switch then 
            print ("*** Results for: "..name.." ***")
        end
        print_menu(name, doclist, showall)
    end
end

return {
    view_file       = view_file,
    deliver_results = deliver_results,
}