module Network.CrawlChain.CrawlChain (
  crawlChain, crawlChains, -- primary interface
  executeActions, crawlForUrl, -- legacy, deprecated
  executeCrawlChain -- visible for tests
  ) where

import Data.List (intersperse)
import Data.List.Split (splitOn)
import System.Environment (getArgs, getProgName)
import System.Exit (exitFailure)

import Network.CrawlChain.CrawlAction
import Network.CrawlChain.CrawlingParameters
import Network.CrawlChain.CrawlChains
import Network.CrawlChain.CrawlingContext (defaultContext, storingContext)
import Network.CrawlChain.DirectiveChainResult (extractFirstResult)
import Network.CrawlChain.Downloading
import Network.CrawlChain.Storing
import Network.CrawlChain.BasicTemplates

executeActions :: CrawlingParameters -> String -> String -> IO ()
executeActions args dir fName = do
  downloadAction <- crawlChain args
  if paramDoDownload args
    then downloadStep dir fName downloadAction
    else storeDownloadAction "external-load" (Just dir ) fName downloadAction

crawlForUrl :: CrawlingParameters -> IO (Maybe String)
crawlForUrl args = do
  crawlResult <- crawlChain args
  case crawlResult of
       (Just (GetRequest url)) -> return $ Just url
       (Just _) -> putStrLn "POST result processing not implemented" >> return Nothing
       Nothing -> return Nothing

{-|
 Returns only the first result of a completely matching branch of the crawling directive.
-}
crawlChain :: CrawlingParameters -> IO (Maybe CrawlAction)
crawlChain args = do
  results <- crawlChains args
  logAndReturnFirstOk results

{-|
 Returns all possible results of the craling directive - meant to be used with lazyness in mind as needed.
-}
crawlChains :: CrawlingParameters -> IO [DirectiveChainResult]
crawlChains args =
      executeCrawlChain context (paramInitialAction args) (paramCrawlDirective args)
        where
          context = if paramDoStore args then storingContext else defaultContext

downloadStep :: String -> String -> Maybe CrawlAction -> IO ()
downloadStep dir fName downloadAction = maybe (return ()) (downloadTo (Just dir) fName) downloadAction

logAndReturnFirstOk :: [DirectiveChainResult] -> IO (Maybe CrawlAction)
logAndReturnFirstOk results = do
  firstOk <- (return . extractFirstResult) results
  putDetailsOnFailure firstOk results
  return firstOk

putDetailsOnFailure :: Maybe CrawlAction -> [DirectiveChainResult] -> IO ()
putDetailsOnFailure firstSuccess results =
  case firstSuccess of
   Just a -> putStr "  Using result: " >> print a
   Nothing -> do
     putStrLn $ "  No results found - details: " ++ showAllFailures where
       showAllFailures = concat $ intersperse "\n\n" $ map showResultPath results