--[[

/*
 *  Baltisot
 *  Copyright (C) 1999-2007 Nicolas "Pixel" Noble
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/* $Id: xmllib.lua,v 1.8 2007-05-30 17:59:50 pixel Exp $ */

]]--

local xml_replacements = {
    { "&", "&" },
    { "<", "&lt;" },
    { ">", "&gt;" },
}

local attribute_replacements = {
    { '"', '\\"' },
}

local function generic_escape(str, replacements)
    local _, r
    
    for _, r in pairs(replacements) do
        str = string.gsub(str, r[1], r[2])
    end
    
    return str
end

local function xml_escape(str)
    return generic_escape(str, xml_replacements)
end

local function attribute_escape(str)
    return generic_escape(str, attribute_replacements)
end

local function process_comment(xm, a)
    return {
        istop = true,
        nodes = {
            a
        },
        type = "comment",
    }
end

local function process_lf(xm)
    return {
        istop = true,
        type = "lf",
    }
end

local function burrow(xm, t)
    local k, v
    
    if type(t) ~= "table" then return end
    if type(t.istop) ~= "boolean" then return end
    
    t.istop = nil
end

local function clean_tops(t)
    local k, v
    
    for k, v in pairs(t) do
        if not v.istop then
            t[k] = nil
        end
    end
end

local function process_tag(xm, key, a)
    local ret, attrs, nodes, has_nodes, has_attrs, k, v, b = { istop = true, key = key }, {}, {}, false, false
    
    if type(a) == "string" then
        a = { a }
    end
    
    if type(a) == "nil" then
        a = {}
    end
    
    if type(a) ~= "table" then
        error("Wrong argument type: " .. type(a))
    end

    if a.__objname == nil then    
        for k, v in ipairs(a) do
            if type(v) == "table" then
                burrow(xm, v)
                has_nodes = true
                table.insert(nodes, v)
            elseif type(v) == "string" then
                has_nodes = true
                table.insert(nodes, xml_escape(v))
            else
                error "Unsupported argument type."
            end
        end
        for k, v in pairs(a) do
            if (type(k) == "string") then
                has_attrs = true
                attrs[k] = attribute_escape(xml_escape(v))
            end
        end
    else
        if a.__objname == "Handle" then
            has_nodes = true
            table.insert(nodes, a)
        else
            error "Can't handle objects which are not Handles."
        end
    end

    if (has_nodes) then ret.nodes = nodes end
    if (has_attrs) then ret.attrs = attrs end

    table.insert(xm.tops, ret)
    
    clean_tops(xm.tops)
    
    return ret
end

local function render_attrs(t)
    local r, k, v = ""
    
    if type(t) ~= "table" then return "" end
    
    for k, v in pairs(t) do
        if v ~= "" then
            r = r .. " " .. k .. '="' .. v .. '"'
        else
            r = r .. " " .. k
        end
    end
    
    return r
end

local function space_indent(depth)
    return string.rep(" ", 4 * depth)
end

local function do_render_r(v, depth)
    local middle, i, n = ""
    
    if v.__objname == "Handle" then
        local r = ""
        while not v:isclosed() do
            r = r .. v:read() .. "\n"
        end
        return r
    elseif v.type == "comment" then
        return space_indent(depth) .. "<!-- " .. v.nodes[1] .. " -->\n"
    elseif v.type == "lf" then
        return "\n"
    elseif type(v.key) == "string" then
        if type(v.nodes) == "table" then
            for i, n in ipairs(v.nodes) do
                if type(n) == "string" then
                    middle = middle .. "\n" .. n
                elseif type(n) == "table" then
                    middle = middle .. "\n" .. do_render_r(n, depth + 1) .. "\n" .. space_indent(depth)
                end
            end
            return space_indent(depth) .. "<" .. v.key .. render_attrs(v.attrs) .. ">" .. middle .. "</" .. v.key .. ">"
        else
            return space_indent(depth) .. "<" .. v.key .. render_attrs(v.attrs) .. " />"
        end
    else
        error "Inconsistancy in the XML structure."
    end
    
    return ""
end

local function do_render(xm)
    local r, i, n = ""
    
    for i, n in pairs(xm.tops) do
        r = r .. do_render_r(n, 0)
    end

    return xm.doctype .. "\n" .. r .. "\n"
end

local xmlmarkup_metatable = {
    __index = function(xm, key)
        local k = key
        return function(xm, a) return process_tag(xm, k, a) end
    end
}

function NewXmlMarkup()
    local r = {
        comment = process_comment,
        lf = process_lf,
        tops = {},
        render = do_render,
        doctype = '<?xml version="1.0" encoding="UTF-8"?>',
    }
    
    setmetatable(r, xmlmarkup_metatable)
    
    return r
end


--[[ example of use:

result = [[
<?xml version="1.0" encoding="UTF-8"?>
<html>
  <head>
    <title>
Test</title>
  </head>

  <body bgcolor="#ffeedd">
Normal test
    <br />
  
    <b>
Bold test.</b>
  
    <!-- Hi there... -->

  </body>
</html>
]]

xm = NewXmlMarkup()

xm:html {
    xm:head {
        xm:title "Test"
    },
    xm:body {
        bgcolor = "#ffeedd",
    
        "Normal test",
        xm:br(),
        xm:b "Bold test.",
        xm:comment "Hi there...",
    }
}

print(xm:render())

]]--