-- to install: pastebin get 9Li3u4Rc /bin/pkg
version = "1.5.10"

-- check data type
-- "package" a list of files to download
-- "list" a list of packages
-- "unknown" anything else
function type(data)
  if data:match("^/[%Z%C\n]+=[^\n]+\n?") then
    return "package"
  elseif data:match("^[%w%-]+=[%w%-]+\n?") then
    return "list"
  else
    return "unknown"
  end
end

-- recursively resolves names until a paste id is returned
-- if a name fails to resolve, it will be returned
function id(name_or_id)
  if fs.exists("/etc/pkg/names.list") then
    for line in io.lines("/etc/pkg/names.list") do
      local first, last = line:find(name_or_id, 1, true)
      local separator = line:find("=")
      if first == 1 and last == (separator - 1) then
        return id(line:sub(separator + 1))
      end
    end
  end
  return name_or_id
end

function append(path, data)
  local file = io.open(path, "a")
  if not file then error("Failed to open " .. path) end
  file:write(data .. "\n")
  file:close()
end

function save(path, data)
  local file = io.open(path, "w")
  if not file then error("Failed to open " .. path) end
  file:write(data)
  file:close()
end

-- downloads pastes by id, returning their data, or erroring
function down(id)
  local response = http.get(
    "https://pastebin.com/raw/"..textutils.urlEncode(id).."?cb="..("%x"):format(math.random(0, 2^30)),
    { ["User-Agent"] = "pkg v" .. version }
  )
  if response and response.getResponseCode() == 200 then
    local data = response.readAll()
    response.close()
    append("/etc/pkg/ids.list", id)
    return data
  else
    error("Failed to download https://pastebin.com/" .. id .. "\nIs " .. id .. " a valid paste id? You may be missing dependencies.")
  end
end

-- adds a list of new packages to the master list
function src(data)
  local sources = {}
  if fs.exists("/etc/pkg/names.list") then
    for line in io.lines("/etc/pkg/names.list") do
      local s = line:find("=")
      sources[line:sub(1, s - 1)] = line:sub(s + 1)
    end
  end
  for line in data:gmatch("([^\n]+)\n?") do
    local s = line:find("=")
    if s then
      sources[line:sub(1, s - 1)] = line:sub(s + 1)
    else
      print("Invalid source: " .. line)
    end
  end
  local file = io.open("/etc/pkg/names.list", "w")
  if not file then error("Failed to open /etc/pkg/names.list") end
  for k,v in pairs(sources) do
    file:write(k .. "=" .. v .. "\n")
  end
  file:close()
end

-- recursively handles getting any source lists, packages, or files
-- path is used for saving files only
function get(name_or_id, path)
  local data = down(id(name_or_id))
  local pkg_type = type(data)
  if pkg_type == "package" then
    print("Getting package: " .. name_or_id)
    for line in data:gmatch("([^\n]+)\n?") do
      local s = line:find("=")
      if s then
        local name_or_id = line:sub(s + 1)
        path = line:sub(1, s - 1)
        print("Downloading " .. name_or_id .. " to " .. path)
        get(name_or_id, path)
      else
        print("Invalid file: " .. line)
      end
    end
    save("/etc/pkg/" .. name_or_id, data)
  elseif pkg_type == "list" then
    print("Adding sources: " .. name_or_id)
    src(data)
  else
    if not path then
      path = "/" .. name_or_id
      save("/etc/pkg/" .. name_or_id, path .. "=" .. name_or_id)
    end
    save(path, data)
  end
end

local function usage()
  print("cc-pkg v"..version.."\nUsage:\n pkg get|run <package|id> <path>\nInstall or run a package or file by pastebin ID. Paths are used for files only.")
end

if not fs.exists("/etc/pkg/names.list") then
  save("/etc/pkg/ids.list", "9Li3u4Rc\n")
  save("/etc/pkg/pkg", "/bin/pkg=9Li3u4Rc")
  get("AH4zw4n0") -- default packages list
end

local arg = {...}
if #arg < 1 then usage() return end
local command = table.remove(arg, 1) or ""
-- command -> get | src | run | put
-- arg[1]  -> name_or_id
-- arg[2]  -> path

if #command > 0 and fs.exists("/lib/pkg-commands/"..command) then
  shell.run("/lib/pkg-commands/"..command, unpack(arg))
elseif command == "get" or command == "src" or command == "run" then
  get(unpack(arg))
  if command == "run" then
    local path = shell.resolve(arg[2] or arg[1]) -- specified path or package name might be its main binary name
    if not path then path = shell.resolve(id(arg[1])) end -- last chance, maybe the resolved paste id is accessible
    if path then
      shell.run(path)
    else
      error("Could not determine what to run.")
    end
  end
elseif command == "put" then
  print("Not implemented.")
else
  usage()
end