--   This file is part of Reno desktop.
--
--  Reno desktop 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 3 of the License, or (at your option) any later version.
--
--  Reno desktop 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 Reno desktop. If not, see <https://www.gnu.org/licenses/>. 

-- Various utilitiy parsers
local parsers = {}

local function split_strings(text)
    -- probably the cleanest function to split by strings i've written to date
    local split = {}
    while text:find("\"") do
        local strstart = text:find("\"")
        while text:sub(strstart-1,strstart-1) == "\\" do
            strstart = text:find("\"",strstart+1)
        end
        local strend = text:find("\"",strstart+1)
        while text:sub(strend-1,strend-1) == "\\" do
            strend = text:find("\"",strend+1)
        end
        if not strend then
            return nil, "String not closed at "..strstart
        end
        local before_string = text:sub(1,strstart-1)
        local string = text:sub(strstart,strend):gsub("\\\"","\"")
        text = text:sub(strend+1,-1)
        table.insert(split,before_string)
        table.insert(split,string)
    end
    table.insert(split,text)
    return split
end

parsers.fast_split_yaml = function(cfgtext)
    -- Fast yaml splitter - incomplete parsing, only first layer is parsed
    -- Used within timers to find objects while decreasing CPU usage
    local items = {}
    local replacements = 1
    cfgtext = cfgtext:gsub("^%s*","")
    while replacements > 0 do
        cfgtext,replacements = cfgtext:gsub("^(.-\n)(%S+)",function(struct,n)
            table.insert(items,struct)
            return ""..n
        end)
    end
    table.insert(items,cfgtext)
    return items
end
parsers.yaml_pseudo = function(cfgtext)
    -- Somewhat yaml-like structure used by pactl
    local struct = {}
    local lines = {}
    cfgtext:gsub("(%s*)([^\n]*)",function(spacing,line)
        table.insert(lines,
            {
                spacing:len(),
                -- key
                line:match("^([^:=]-)%s*[:=]") or line,
                -- value
                line:match(":%s*(.-)%s*$") or
                line:match("=%s*(.-)%s*$")
            }
        )
    end)
    local history = {struct}
    local spacing_width = 0
    for k,v in pairs(lines) do
        if v[1] > spacing_width then
            history[#history][lines[k-1][2]] = {
                [lines[k-1][2]] = lines[k-1][3]
            }
            history[#history+1] = history[#history][lines[k-1][2]]
        elseif v[1] < spacing_width then
            history[#history] = nil
        end
        if v[3] and v[3]:match("^%s*\".*\"%s*$") then
            history[#history][v[2]] = v[3]:match("^%s*\"(.*)\"%s*$")
        else
            history[#history][v[2]] = v[3]
        end
        spacing_width = v[1]
    end
    return struct
end

local function quotestrip(txt)
    if (txt:sub(1,1):match("['\"]"))
        and (txt:sub(-1,-1) == txt:sub(1,1)) then
        return txt:sub(2,-2)
    else
        return txt
    end
end


parsers.conf = function(cfgtext)
    -- Conf style parser (not exactly TOML)
    cfgtext = cfgtext:gsub("#[^\n]*","")
    local split_by_strings,err = split_strings(cfgtext)
    if not split_by_strings then error(err) end
    local full_split = {{}}
    local current_line = full_split[1]
    -- tokenizer
    for _,v in pairs(split_by_strings) do
        v = v:match("^[ \t]*(.*)[ \t]*$")
        if (not (v == "")) then
            if not v:match("^\".*\"$") then
                v:gsub("[^ \t]+",function(text)
                    while text:match("\n") do
                        local before,after = text:match("([^\n]*)\n(.*)")
                        if before ~= "" then
                            table.insert(current_line,before)
                        end
                        if #current_line > 0 then
                            table.insert(full_split,{})
                            current_line = full_split[#full_split]
                        end
                        text = after
                    end
                    if text ~= "" then
                        table.insert(current_line,text)
                    end
                end)
            else
                table.insert(current_line,v)
            end
        end
    end
    table.remove(full_split,#full_split)
    local struct = {global = {}}
    local block = "global"
    -- parser
    for _,line in pairs(full_split) do
        if line[1] and line[1]:match("^%[[^%]]+%]$") then -- block
            block = line[1]:match("^%[([^%]]+)%]$")
            struct[block] = {}
        elseif #line == 3 then -- assignment
            if (line[3]:sub(1,1):match("['\"]")) -- string
                and (line[3]:sub(-1,-1) == line[3]:sub(1,1)) then
                struct[block][quotestrip(line[1])] = quotestrip(line[3])
            elseif line[3]:match("^%d+$") then -- number
                struct[block][quotestrip(line[1])] = tonumber(line[3])
            elseif (line[3] == "true") or (line[3] == "false") then -- boolean
                struct[block][quotestrip(line[1])] = (line[3] == "true")
            else
                error("Invalid assignment expression: "..line[3])
            end
        else -- invalid
            local textline = ""
            for _,v in pairs(line) do
                textline = textline..v.." "
            end
            error("Invalid config expression: "..textline:sub(1,-2))
        end
    end
    return struct
end
return parsers