--[[ GRAPH widget
This is a modified graph widget originally built off of scripts found at the site below, modified by me (McLovin). Anyone may use, or modify this script any way, just please give credit to the original authors, (wlourf and McLovin)
    http://u-scripts.blogspot.com/2010/10/graph-widget.html
    
To call the script in a conky, use, before TEXT
    lua_load /path/to/the/script/graph.lua
    lua_draw_hook_pre main_graph
and add one line (blank or not) after TEXT


Parameters are :
3 parameters are mandatory
name        - the name of the conky variable to display,
              for example for {$cpu cpu0}, just write name="cpu"
arg            - the argument of the above variable,
              for example for {$cpu cpu1}, just write arg="cpu1"
                arg can be a numerical value if name=""
max            - the maximum value the above variable can reach,
              for example for {$cpu cpu1}, just write max=100 or less or more
    
Optional parameters:
x,y         - coordinates of the bottom-left corner of the graph,
              relative to the top-left corner of the conky window 
              default =  bottom-left corner of the conky window
width       - width of the graph, default = 100 pixels
height      - height of the graph, default = 20 pixels
nb_values   - number of values to display in the graph, default=width 
              i.e. 1 pixel for 1 value
autoscale   - if set to true, calculate the max valeu of the y axis and
              doesn't use the max parameter above, default=false
skew_x      - skew graph around x axis, défaut = 0
skew_y      - skew graph around y axis, défaut = 0
angle        - angle of rotation of the graph in degress, default = 0
              i.e. a horizontal graph)
inverse     - if set to true, graph are draw from right to left, default=false
background  - if set to false, background is not drawn, default=true
foreground  - if set to false, foreground is not drawn, default=true
              foreground = plain graph
bg_bd_size  - size of the border of the background, default=0=no border
fg_bd_size  - size of the border of the foreground, default=0=no border


Colours tables below are defined into braces :
{position in the gradient (0 to 1), colour in hexadecimal, alpha (0 to 1)}
example for a single colour table : 
{{0,0xFFAA00,1}} position parameter doesn't matter
example for a two-colours table : 
{{0,0xFFAA00,1},{1,0x00AA00,1}} or {{0.5,0xFFAA00,1},{1,0x00AA00,1}}
example for a three-colours table : 
{{0,0xFFAA00,1},{0.5,0xFF0000,1},{1,0x00AA00,1}}

bg_colour    - colour table for background,
              default = {{0,0x000000,.5},{1,0xFFFFFF,.5}}
fg_colour    - colour table for foreground,
              default = {{0,0x00FFFF,1},{1,0x0000FF,1}}
bg_bd_colour- colour table for background border,
              default = {{1,0xFFFFFF,1}}              
fg_bd_colour- colour table for foreground border,
              default = {{1,0xFFFF00,1}}              

bg_orientation, bg_bd_orientation, fg_orientation, fg_bd_orientation,
            - "orientation" defines the starting point of the gradient,
              default="nn"
              there are 8 available starting points : 
              "nw","nn","ne","ee","se","ss","sw","ww"
              (n for north, w for west ...)
              theses 8 points are the 4 corners + the 4 middles of graph
              so a gradient "nn" will go from "nn" to "ss"
              a gradient "nw" will go from "nw" to "se"

draw_me     - if set to false, graph is not drawn (default = true)
              it can be used with a conky string, if the string returns 1, the graph is drawn :
              example : "${if_empty ${wireless_essid wlan0}}${else}1$endif",
              
                  text is parsed inside the function, not in the array of settings
v1.0 © McLovin Oct. 15, 2012
--      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 version 3 (GPLv3)
--     
--      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., 51 Franklin Street, Fifth Floor, Boston,
--      MA 02110-1301, USA.        

]]

require 'cairo'

function set_settings()
    graph_settings={
        { --quad graph
        name="cpu",
        arg="cpu1",
        max=100,
        x=140,
        y=135,
        autoscale=true,
        width=220,
        height=75,
        nb_values=100,
        fg_bd_size=0.5,
        --bg_colour = {{0,0x007AF6,0.5},{1,0xFFFFFF,0.5}},
        fg_bd_colour = { {0,0xFFA209,1},{0.5,0xFFA209,1},{1,0xFFA209,1}},
        foreground=false
        },
        {
        name="cpu",
        arg="cpu2",
        max=100,
        x=140,
        y=135,
        autoscale=true,
        width=220,
        height=75,
        nb_values=100,
        fg_bd_size=0.5,
        --bg_bd_size=2,
        --bg_bd_colour = { {0,0x0000ff,1},{1,0xfffff,1}},
        fg_bd_colour = { {0,0xF6000F,1},{0.5,0xF6000F,1},{1,0xF6000F,1}},
        foreground=false,
        background=false,
        },
        {
        name="cpu",
        arg="cpu3",
        max=100,
        x=140,
        y=135,
        autoscale=true,
        width=220,
        height=75,
        nb_values=100,
        fg_bd_size=0.5,
        --bg_bd_size=2,
        --bg_bd_colour = { {0,0x0000ff,1},{1,0xfffff,1}},
        fg_bd_colour = { {0,0x00F615,1},{0.5,0x00F615,1},{1,0x00F615,1}},
        foreground=false,
        background=false,
        },        {
        name="cpu",
        arg="cpu4",
        max=100,
        x=140,
        y=135,
        autoscale=true,
        width=220,
        height=75,
        nb_values=100,
        fg_bd_size=0.5,
        --bg_bd_size=2,
        --bg_bd_colour = { {0,0x0000ff,1},{1,0xfffff,1}},
        fg_bd_colour = { {0,0x2A95B4,1},{0.5,0x2A95B4,1},{1,0x2A95B4,1}},
        foreground=false,
        background=false,
        },

        --ethernet graphs
            {
        name="upspeedf",
        arg="eth0",
        max=60,
            x=10,
        y=670,
        autoscale=true,
        width=330,
        height=40,
        --bg_colour = {{0,0x30EC17,0.5},{1,0xFFFFFF,0.5}},
        fg_colour = { {0,0xFF0000,1},{0.5,0xFFA209,1},{1,0x2A95B4,1}},
        },
        {
        name="downspeedf",
        arg="eth0",
        max=60,
            x=10,
        y=750,
        autoscale=true,
        width=330,
        height=40,
        --bg_colour = {{0,0x30EC17,0.5},{1,0xFFFFFF,0.5}},
        fg_colour = { {0,0xFF0000,1},{0.5,0xFFA209,1},{1,0x2A95B4,1}},
        },                                                                            }
end


function check_settings(t)
    --tables are check only when conky start
    if t.name==nil and t.arg==nil then 
        print ("No input values ... use parameters 'name'" .. 
            " with 'arg' or only parameter 'arg' ") 
        return 1
    end

    if t.max==nil then
        print ("No maximum value defined, use 'max'")
        print ("for name=" .. t.name .. " with arg=" .. t.arg)
        return 1
    end
    if t.name==nil then t.name="" end
    if t.arg==nil then t.arg="" end
    return 0
end

function conky_main_graph()

    if conky_window == nil then return end
        
    local w=conky_window.width
    local h=conky_window.height
    local cs=cairo_xlib_surface_create(conky_window.display, 
            conky_window.drawable, conky_window.visual, w, h)
    cr=cairo_create(cs)

    updates=tonumber(conky_parse('${updates}'))
    --start drawing after "updates_gap" updates
    --prevent segmentation error for cpu
    updates_gap=5
    if updates==1 then    
        set_settings()
        
        flagOK=0
        for i in pairs(graph_settings) do
            if graph_settings[i].width==nil then graph_settings[i].width=100 end
            if graph_settings[i].nb_values==nil then  
                graph_settings[i].nb_values= graph_settings[i].width
            end
            --create an empty table to store values
            graph_settings[i]["values"]={}
            --beginning point
            graph_settings[i].beg = graph_settings[i].nb_values
            --graph_settings[i].beg = 0
            for j =1, graph_settings[i].nb_values do
                graph_settings[i].values[j]=0
            end
            graph_settings[i].flag_init=true
            flagOK=flagOK + check_settings(graph_settings[i])

        end
    end

    if flagOK>0 then 
        --abort script if error in one of the tables
        print ("ERROR : Check the graph_setting table")
        return
    end

    --drawing process
    if updates > updates_gap then
        for i in pairs(graph_settings) do
            if graph_settings[i].draw_me==true then graph_settings[i].draw_me = nil end
            if (graph_settings[i].draw_me==nil or conky_parse(tostring(graph_settings[i].draw_me)) == "1") then 
                local nb_values=graph_settings[i].nb_values
                graph_settings[i].automax=0
                for j =1, nb_values do
                    if graph_settings[i].values[j+1]==nil then 
                        graph_settings[i].values[j+1]=0 
                    end
                
                    graph_settings[i].values[j]=graph_settings[i].values[j+1]
                    if j==nb_values then
                        --store value
                        if graph_settings[i].name=="" then
                            value=graph_settings[i].arg
                        else
                            value=tonumber(conky_parse('${' .. 
                                graph_settings[i].name .. " " ..
                                graph_settings[i].arg ..'}'))
                        end
                        graph_settings[i].values[nb_values]=value
                    end
                    graph_settings[i].automax=math.max(graph_settings[i].automax,
                                                       graph_settings[i].values[j])
                    --should stop weird glitches at beginning when no values reported yet for upspeed or diskio
                    if graph_settings[i].automax == 0 then graph_settings[i].automax = 1 end 
                end
                   draw_graph(graph_settings[i])
            end
        end
    end

    cairo_destroy(cr)
    cairo_surface_destroy(cs)
    updates=nil
    updates_gap=nil
end


function draw_graph(t)
    --drawing function

    local function rgb_to_r_g_b(colour)
        return ((colour[2] / 0x10000) % 0x100) / 255., ((colour[2] / 0x100) % 0x100) / 255., (colour[2] % 0x100) / 255., colour[3]
    end
 
    local function linear_orientation(o,w,h)
        --set gradient for bg and bg border
        local p
        if o=="nn" then
            p={w/2,h,w/2,0}
        elseif o=="ne" then
            p={w,h,0,0}
        elseif o=="ww" then
            p={0,h/2,w,h/2}
        elseif o=="se" then
            p={w,0,0,h}
        elseif o=="ss" then
            p={w/2,0,w/2,h}
        elseif o=="ee" then
            p={w,h/2,0,h/2}        
        elseif o=="sw" then
            p={0,0,w,h}
        elseif o=="nw" then
            p={0,h,w,0}
        end
        return p
    end

    local function linear_orientation_inv(o,w,h)
        --set gradient for fg and fg border
        local p
        if o=="ss" then
            p={w/2,h,w/2,0}
        elseif o=="sw" then
            p={w,h,0,0}
        elseif o=="ee" then
            p={0,h/2,w,h/2}
        elseif o=="nw" then
            p={w,0,0,h}
        elseif o=="nn" then
            p={w/2,0,w/2,h}
        elseif o=="ww" then
            p={w,h/2,0,h/2}        
        elseif o=="ne" then
            p={0,0,w,h}
        elseif o=="se" then
            p={0,h,w,0}
        end
        return p
    end


    --set default values
    
    --cancel drawing if not needed
    if t.draw_me~=nil and conky_parse(tostring(t.draw_me)) ~= "1" then 
        return
    end
    

    
    if t.height==nil    then t.height=20 end
    --checked in previous part : width and nb_values
        
    if t.background==nil    then t.background=true end
    if t.bg_bd_size==nil    then t.bg_bd_size=0 end
    if t.x==nil             then t.x=t.bg_bd_size end
    if t.y==nil             then t.y=conky_window.height -t.bg_bd_size end
    if t.bg_colour==nil     then t.bg_colour={{0,0x000000,.0},{1,0xFFFFFF,.0}} end
    if t.bg_bd_colour==nil     then t.bg_bd_colour={{1,0xFFFFFF,0}} end
    
    if t.foreground==nil    then t.foreground=true end
    if t.fg_colour==nil     then t.fg_colour={{0,0x00FFFF,1},{1,0x0000FF,1}} end
    
    if t.fg_bd_size==nil    then t.fg_bd_size=0 end    
    if t.fg_bd_colour==nil  then t.fg_bd_colour={{1,0xFFFF00,1}} end
    
    if t.autoscale==nil     then t.autoscale=false end
    if t.inverse==nil       then t.inverse=false end
    if t.angle==nil         then t.angle=0 end
    
    if t.bg_bd_orientation==nil then t.bg_bd_orientation="nn" end
    if t.bg_orientation==nil then t.bg_orientation="nn" end
    if t.fg_bd_orientation==nil then t.fg_bd_orientation="nn" end
    if t.fg_orientation==nil then t.fg_orientation="nn" end

    --check colours tables
    for i=1, #t.fg_colour do    
        if #t.fg_colour[i]~=3 then 
            print ("error in fg_colour table")
            t.fg_colour[i]={1,0x0000FF,1} 
        end
    end
    
    for i=1, #t.fg_bd_colour do    
        if #t.fg_bd_colour[i]~=3 then 
            print ("error in fg_bd_colour table")
            t.fg_bd_colour[i]={1,0x00FF00,1} 
        end
    end
    
    for i=1, #t.bg_colour do    
        if #t.bg_colour[i]~=3 then 
            print ("error in background color table")
            t.bg_colour[i]={1,0xFFFFFF,0.0} 
        end
    end    

    for i=1, #t.bg_bd_colour do    
        if #t.bg_bd_colour[i]~=3 then 
            print ("error in background border color table")
            t.bg_bd_colour[i]={1,0xFFFFFF,0} 
        end
    end    

    --calculate skew parameters if needed
    if t.flag_init then
        if t.skew_x == nil then 
            t.skew_x=0 
        else
            t.skew_x = math.pi*t.skew_x/180    
        end
        if t.skew_y == nil then 
            t.skew_y=0
        else
            t.skew_y = math.pi*t.skew_y/180    
        end
        t.flag_init=false
    end

    cairo_set_line_cap(cr,CAIRO_LINE_CAP_ROUND)
    cairo_set_line_join(cr,CAIRO_LINE_JOIN_ROUND)

    local matrix0 = cairo_matrix_t:create()
    tolua.takeownership(matrix0)
    cairo_save(cr)
    cairo_matrix_init (matrix0, 1,t.skew_y,t.skew_x,1,0,0)
    cairo_transform(cr,matrix0)
    
       local ratio=t.width/t.nb_values

    cairo_translate(cr,t.x,t.y)
    cairo_rotate(cr,t.angle*math.pi/180)
    cairo_scale(cr,1,-1)

    --background
    if t.background then
        local pts=linear_orientation(t.bg_orientation,t.width,t.height)
        local pat = cairo_pattern_create_linear (pts[1],pts[2],pts[3],pts[4])
        for i=1, #t.bg_colour do
            --print ("i",i,t.colour[i][1], rgb_to_r_g_b(t.colour[i]))
            cairo_pattern_add_color_stop_rgba (pat, t.bg_colour[i][1], rgb_to_r_g_b(t.bg_colour[i]))
        end
        cairo_set_source (cr, pat)
        cairo_rectangle(cr,0,0,t.width,t.height)    
        cairo_fill(cr)    
        cairo_pattern_destroy(pat)
    end
    
    --autoscale
    cairo_save(cr)
    if t.autoscale then
        t.max= t.automax*1.1
    end
    
    local scale_x = t.width/(t.nb_values-1)
    local scale_y = t.height/t.max
    
    --define first point of the graph
    if updates-updates_gap <t.nb_values then 
        t.beg = t.beg - 1
        --next line prevent segmentation error when conky window is redraw 
        --quicly when another window "fly" over it
        if t.beg<0 then t.beg=0 end
    else
        t.beg=0
    end
    if t.inverse then cairo_scale(cr,-1,1)
    cairo_translate(cr,-t.width,0) end

    --graph foreground
    if t.foreground then
        local pts_fg=linear_orientation_inv(t.fg_orientation,t.width,t.height)
        local pat = cairo_pattern_create_linear (pts_fg[1],pts_fg[2],pts_fg[3],pts_fg[4])
        for i=1,#t.fg_colour,1 do
            cairo_pattern_add_color_stop_rgba (pat, 1-t.fg_colour[i][1], rgb_to_r_g_b(t.fg_colour[i]))
        end
        cairo_set_source (cr, pat)

        cairo_move_to(cr,t.beg*scale_x,0)
        cairo_line_to(cr,t.beg*scale_x,t.values[t.beg+1]*scale_y)
        for i=t.beg, t.nb_values-1 do
            cairo_line_to(cr,i*scale_x,t.values[i+1]*scale_y)        
        end
        cairo_line_to(cr,(t.nb_values-1)*scale_x,0)
        cairo_close_path(cr)
        cairo_fill(cr)
        cairo_pattern_destroy(pat)
    end

    --graph_border
    if t.fg_bd_size>0 then
        local pts=linear_orientation_inv(t.fg_bd_orientation,t.width,t.height)
        local pat = cairo_pattern_create_linear (pts[1],pts[2],pts[3],pts[4])
        for i=1,#t.fg_bd_colour,1 do
            cairo_pattern_add_color_stop_rgba (pat, 1-t.fg_bd_colour[i][1], rgb_to_r_g_b(t.fg_bd_colour[i]))
        end
        cairo_set_source (cr, pat)
        cairo_move_to(cr,t.beg*scale_x,t.values[t.beg+1]*scale_y)
        for i=t.beg, t.nb_values-1 do
            cairo_line_to(cr,i*scale_x,t.values[i+1]*scale_y)        
        end
        cairo_set_line_width(cr,t.fg_bd_size)
        cairo_stroke(cr)
        cairo_pattern_destroy(pat)
    end
    cairo_restore(cr)

    --background border
    if t.bg_bd_size>0 then
        local pts=linear_orientation(t.bg_bd_orientation,t.width,t.height)
        local pat = cairo_pattern_create_linear (pts[1],pts[2],pts[3],pts[4])
        for i=1, #t.bg_bd_colour do
            --print ("i",i,t.colour[i][1], rgb_to_r_g_b(t.colour[i]))
            cairo_pattern_add_color_stop_rgba (pat, t.bg_bd_colour[i][1], rgb_to_r_g_b(t.bg_bd_colour[i]))
        end
        cairo_set_source (cr, pat)
        cairo_rectangle(cr,0,0,t.width,t.height)    
        cairo_set_line_width(cr,t.bg_bd_size)
        cairo_stroke(cr)
        cairo_pattern_destroy(pat)    
    end    

    cairo_restore(cr)

end