local env = require 'argcheck.env'
local sdascii
pcall(function()
         sdascii = require 'sundown.ascii'
      end)

local usage = {}

local function generateargp(rules)
   local txt = {}
   for idx, rule in ipairs(rules) do
      local isopt = rule.opt or rule.default ~= nil or rules.defauta or rule.defaultf
      table.insert(txt,
                   (isopt and '[' or '')
                      .. ((idx == 1) and '' or ', ')
                      .. rule.name
                      .. (isopt and ']' or ''))
   end
   return table.concat(txt)
end

local function generateargt(rules)
   local txt = {}
   table.insert(txt, '```')
   table.insert(txt, string.format(
                   '%s%s',
                   rules.noordered and '' or '(',
                   rules.nonamed and '' or '{'))

   local size = 0
   for _,rule in ipairs(rules) do
      size = math.max(size, #rule.name)
   end
   local arg = {}
   local hlp = {}
   for _,rule in ipairs(rules) do
      table.insert(arg,
                   ((rule.opt or rule.default ~= nil or rule.defaulta or rule.defaultf) and '[' or ' ')
                   .. rule.name .. string.rep(' ', size-#rule.name)
                   .. (rule.type and (' = ' .. rule.type) or '')
                .. ((rule.opt or rule.default ~= nil or rule.defaulta or rule.defaultf) and ']' or '')
          )
      local default = ''
      if rule.defaulta then
         default = string.format(' [defaulta=%s]', rule.defaulta)
      elseif rule.defaultf then
         default = string.format(' [has default]')
      elseif type(rule.default) ~= 'nil' then
         if type(rule.default) == 'string' then
            default = string.format(' [default=%s]', rule.default)
         elseif type(rule.default) == 'number' then
            default = string.format(' [default=%s]', rule.default)
         elseif type(rule.default) == 'boolean' then
            default = string.format(' [default=%s]', rule.default and 'true' or 'false')
         else
            default = ' [has default value]'
         end
      end
      table.insert(hlp, (rule.help or '') .. (rule.doc or '') .. default)
   end

   local size = 0
   for i=1,#arg do
      size = math.max(size, #arg[i])
   end

   for i=1,#arg do
      table.insert(txt, string.format("  %s %s -- %s", arg[i], string.rep(' ', size-#arg[i]), hlp[i]))
   end
   table.insert(txt, string.format(
                   '%s%s',
                   rules.nonamed and '' or '}',
                   rules.noordered and '' or ')'))
   table.insert(txt, '```')

   txt = table.concat(txt, '\n')

   return txt
end

function usage.render(doc)
   -- We render any markdown in the input into ANSI color codes using sundown, but only if stdout and stderr are terminals
   if sdascii and pcall(require, 'torch') and torch.isatty(io.stderr) and torch.isatty(io.stdout) then
      doc = sdascii.render(doc)
   end

   return doc
end

function usage.usage(truth, rules, ...)
   if truth then
      local norender = select(1, ...)
      local doc = rules.help or rules.doc

      if doc then
         doc = doc:gsub('@ARGP',
                        function()
                           return generateargp(rules)
                        end)

         doc = doc:gsub('@ARGT',
                        function()
                           return generateargt(rules)
                        end)
      end

      if not doc then
         doc = '\n*Arguments:*\n' .. generateargt(rules)
      end

      return doc
   else
      local self = rules
      local args = {}
      for i=1,select('#', ...) do
         table.insert(args, string.format("**%s**", env.type(select(i, ...))))
      end
      local argtblidx
      if self:hasruletype('N') then
         if select("#", ...) == 1 and env.istype(select(1, ...), "table") then
            argtblidx = 1
         end
      elseif self:hasruletype('M') then
         if select("#", ...) == 2 and env.istype(select(2, ...), "table") then
            argtblidx = 2
         end
      end
      if argtblidx then
         local argtbl = {}
         local tbl = select(argtblidx, ...)
         local n = 0
         for k,v in pairs(tbl) do
            n = n + 1
            if n > 20 then
               table.insert(argtbl, '...')
               break
            end
            if type(k) == 'string' then
               table.insert(argtbl, string.format("**%s=%s**", k, env.type(v)))
            else
               table.insert(argtbl, string.format("**[%s]**=?", env.type(k)))
            end
         end
         args[argtblidx] = string.format("**table**={ %s }", table.concat(argtbl, ', '))
      end
      local doc = string.format("*Got:* %s", table.concat(args, ', '))
      return doc
   end
end

return usage