#!/usr/bin/env lua
--[[
--   Draw a bar using unicode
--]]
local width
local colors = {black=0, red=1, green=2, yellow=3, blue=4, magenta=5, cyan=6, white=7}
local function fail(msg)
    io.stderr:write(msg..'\n')
    os.exit(1)
end

local function get_color(str)
    if colors[str] then return ("\x1b[%dm"):format(colors[str]) end
    local r,g,b = str:match("^(%x%x)(%x%x)(%x%x)$")
    if not r then
        r,g,b = str:match("^(%x)(%x)(%x)$")
        r = r.."0"
        g = g.."0"
        b = b.."0"
    end
    if not r then fail("Not a recognized color: "..str) end
    return ("2;%d;%d;%d"):format(tonumber(r,16), tonumber(g,16), tonumber(b,16))
end
local percent
local fg, bg
local before, after = {}, {}
local dest = before
local bits = {" ","▏","▎","▍","▌","▋","▊","▉","█"}
for i,a in ipairs(arg) do
    local num, den = a:match("^([%d.]+)/([%d.]+)$")
    if num then
        percent = tonumber(num)/tonumber(den)
        dest = after
    elseif a:match("^([%d.]+)%%$") then
        percent = tonumber(a:match("^([%d.]+)%%$"))/100
        dest = after
    elseif a:match("^([%d.]+)$") then
        percent = tonumber(a:match("^([%d.]+)"))
        dest = after
    elseif a:match("^--fg=") then
        fg = "\x1b[38;"..get_color(a:match("^--fg=(.*)")).."m"
    elseif a:match("^--bg=") then
        bg = "\x1b[48;"..get_color(a:match("^--bg=(.*)")).."m"
    elseif a:match("^--width=") then
        width = tonumber(a:match("^--width=(.*)"))
    elseif a:match("^-w=") then
        width = tonumber(a:match("^-w=(.*)"))
    elseif a:match("^--scale=") then
        bits = {}
        local delim, rest = a:match("^--scale=(.)(.*)")
        for bit in rest:gmatch("[^"..delim.."]*") do
            table.insert(bits, bit)
        end
    else
        table.insert(dest, a)
    end
end
width = width or 20
if not percent then
    fail("Usage: bar [--width <w>] <percent|a/b>")
end
local x = percent * width
if x < 0 then x = 0 elseif x > width then x = width end
local middle = x == width and "" or bits[1+math.floor(#bits * (x % 1))]
io.write(table.concat(before,''))
if fg then io.write(fg) end
if bg then io.write(bg) end
io.write(bits[#bits]:rep(math.floor(x))..middle..(" "):rep(width-math.floor(x)-1))
if fg or bg then io.write("\x1b[0m") end
io.write(table.concat(after,''))
io.write("\n")