--- Module implementing the LuaRocks "new_version" command.
-- Utility function that writes a new rockspec, updating data from a previous one.
module("luarocks.new_version", package.seeall)

local util = require("luarocks.util")
local cfg = require("luarocks.cfg")
local download = require("luarocks.download")
local fetch = require("luarocks.fetch")
local persist = require("luarocks.persist")
local dir = require("luarocks.dir")
local fs = require("luarocks.fs")

help_summary = "Auto-write a rockspec for a new version of a rock."
help_arguments = "{<package>|<rockspec>} [<new_version>] [<new_url>]"
help = [[
This is a utility function that writes a new rockspec, updating data
from a previous one.

If a package name is given, it downloads the latest rockspec from the
default server. If a rockspec is given, it uses it instead.

If the version number is not given, it only increments the revision
number of the given (or downloaded) rockspec.

If a URL is given, it replaces the one from the old rockspec with the
given URL. If a URL is not given and a new version is given, it tries
to guess the new URL by replacing occurrences of the version number
in the URL or tag. It also tries to download the new URL to determine
the new MD5 checksum.

WARNING: it writes the new rockspec to the current directory,
overwriting the file if it already exists.
]]

local order = {"rockspec_format", "package", "version", 
   { "source", { "url", "tag", "branch", "md5" } },
   { "description", {"summary", "detailed", "homepage", "license" } },
   "supported_platforms", "dependencies", "external_dependencies",
   { "build", {"type", "modules", "copy_directories", "platforms"} },
   "hooks"}

local function try_replace(tbl, field, old, new)
   if not tbl[field] then
      return false
   end
   local old_field = tbl[field]
   local new_field = tbl[field]:gsub(old, new)
   if new_field ~= old_field then
      util.printout("Guessing new '"..field.."' field as "..new_field)
      tbl[field] = new_field
      return true      
   end
   return false
end

local function check_url_and_update_md5(out_rs, out_name)
   out_rs.source.md5 = nil
   local file, temp_dir = fetch.fetch_url_at_temp_dir(out_rs.source.url, "luarocks-new-version-"..out_name)
   if file then
      util.printout("File successfully downloaded. Updating MD5 checksum...")
      out_rs.source.md5 = fs.get_md5(file)
   else
      util.printerr("Warning: invalid URL - "..temp_dir)
   end
end
 
function run(...)
   local flags, input, version, url = util.parse_flags(...)
   if not input then
      return nil, "Missing arguments: expected program or rockspec. See help."
   end
   assert(type(input) == "string")
   
   local filename = input
   if not input:match(".rockspec$") then
      local err
      filename, err = download.download("rockspec", input)
      if not filename then
         return nil, err
      end
   end
   
   local valid_rs, err = fetch.load_rockspec(filename)
   if not valid_rs then
      return nil, err
   end

   local old_ver, old_rev = valid_rs.version:match("(.*)%-(%d+)$")
   local new_ver, new_rev
   
   if version then
      new_ver, new_rev = version:match("(.*)%-(%d+)$")
      new_rev = tonumber(new_rev)
      if not new_rev then
         new_ver = version
         new_rev = 1
      end
   else
      new_ver = old_ver
      new_rev = tonumber(old_rev) + 1
   end
   
   
   local out_rs = persist.load_into_table(filename)
   local out_name = out_rs.package:lower()
   out_rs.version = new_ver.."-"..new_rev
   if url then
      out_rs.source.url = url
      check_url_and_update_md5(out_rs, out_name)
   else
      if new_ver ~= old_ver then
         local ok = try_replace(out_rs.source, "url", old_ver, new_ver)
         if ok then
            check_url_and_update_md5(out_rs, out_name)
         else
            ok = try_replace(out_rs.source, "tag", old_ver, new_ver)
            if not ok then
               return nil, "Failed to determine the location of the new version."
            end
         end
      end
   end
   
   if out_rs.build and out_rs.build.type == "module" then
      out_rs.build.type = "builtin"
   end
   
   local out_filename = out_name.."-"..new_ver.."-"..new_rev..".rockspec"
   
   persist.save_from_table(out_filename, out_rs, order)
   
   util.printout("Wrote "..out_filename)

   local valid_out_rs, err = fetch.load_local_rockspec(out_filename)
   if not valid_out_rs then
      return nil, "Failed loading generated rockspec: "..err
   end
   
   return true
end