{- |
-}

{-# LANGUAGE CPP #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}

module Hledger.Reports.BudgetReport
where

import Data.Decimal
import Data.List
import Data.Maybe
#if !(MIN_VERSION_base(4,11,0))
import Data.Monoid ((<>))
#endif
import Data.Ord
import Data.Time.Calendar
import Safe
--import Data.List
--import Data.Maybe
import qualified Data.Map as Map
import Data.Map (Map)
import qualified Data.Text as T
--import qualified Data.Text.Lazy as TL
--import System.Console.CmdArgs.Explicit as C
--import Lucid as L
import Text.Printf (printf)
import Text.Tabular as T
--import Text.Tabular.AsciiWide

import Hledger.Data
--import Hledger.Query
import Hledger.Utils
--import Hledger.Read (mamountp')
import Hledger.Reports.ReportOptions
import Hledger.Reports.ReportTypes
import Hledger.Reports.BalanceReport (sortAccountItemsLike)
import Hledger.Reports.MultiBalanceReports


-- for reference:
--
--type MultiBalanceReportRow    = (AccountName, AccountName, Int, [MixedAmount], MixedAmount, MixedAmount)
--type MultiBalanceReportTotals = ([MixedAmount], MixedAmount, MixedAmount) -- (Totals list, sum of totals, average of totals)
--
--type PeriodicReportRow a =
--  ( AccountName  -- ^ A full account name.
--  , [a]          -- ^ The data value for each subperiod.
--  , a            -- ^ The total of this row's values.
--  , a            -- ^ The average of this row's values.
--  )

type BudgetGoal    = Change
type BudgetTotal   = Total
type BudgetAverage = Average

-- | A budget report tracks expected and actual changes per account and subperiod.
type BudgetCell = (Maybe Change, Maybe BudgetGoal)
type BudgetReport = PeriodicReport BudgetCell
type BudgetReportRow = PeriodicReportRow BudgetCell

-- | Calculate budget goals from all periodic transactions,
-- actual balance changes from the regular transactions,
-- and compare these to get a 'BudgetReport'.
-- Unbudgeted accounts may be hidden or renamed (see budgetRollup).
budgetReport :: ReportOpts -> Bool -> Bool -> DateSpan -> Day -> Journal -> BudgetReport
budgetReport ropts assrt showunbudgeted reportspan d j =
  let
    q = queryFromOpts d ropts 
    budgetedaccts = 
      dbg2 "budgetedacctsinperiod" $
      accountNamesFromPostings $ 
      concatMap tpostings $ 
      concatMap (flip runPeriodicTransaction reportspan) $ 
      jperiodictxns j
    actualj = dbg1 "actualj" $ budgetRollUp budgetedaccts showunbudgeted j
    budgetj = dbg1 "budgetj" $ budgetJournal assrt ropts reportspan j
    actualreport@(MultiBalanceReport (actualspans, _, _)) = dbg1 "actualreport" $ multiBalanceReport ropts  q actualj
    budgetgoalreport@(MultiBalanceReport (_, budgetgoalitems, budgetgoaltotals)) = dbg1 "budgetgoalreport" $ multiBalanceReport ropts q budgetj
    budgetgoalreport'
      -- If no interval is specified:
      -- budgetgoalreport's span might be shorter actualreport's due to periodic txns; 
      -- it should be safe to replace it with the latter, so they combine well. 
      | interval_ ropts == NoInterval = MultiBalanceReport (actualspans, budgetgoalitems, budgetgoaltotals)
      | otherwise = budgetgoalreport 
    budgetreport = combineBudgetAndActual budgetgoalreport' actualreport
    sortedbudgetreport = sortBudgetReport ropts j budgetreport
  in
    dbg1 "sortedbudgetreport" sortedbudgetreport

-- | Sort a budget report's rows according to options.
sortBudgetReport :: ReportOpts -> Journal -> BudgetReport -> BudgetReport
sortBudgetReport ropts j (PeriodicReport (ps, rows, trow)) = PeriodicReport (ps, sortedrows, trow)
  where
    sortedrows 
      | sort_amount_ ropts && tree_ ropts = sortTreeBURByActualAmount rows
      | sort_amount_ ropts                = sortFlatBURByActualAmount rows
      | otherwise                         = sortByAccountDeclaration rows

    -- Sort a tree-mode budget report's rows by total actual amount at each level.
    sortTreeBURByActualAmount :: [BudgetReportRow] -> [BudgetReportRow] 
    sortTreeBURByActualAmount rows = sortedrows
      where
        anamesandrows = [(first6 r, r) | r <- rows]
        anames = map fst anamesandrows
        atotals = [(a,tot) | (a,_,_,_,(tot,_),_) <- rows]
        accounttree = accountTree "root" anames
        accounttreewithbals = mapAccounts setibalance accounttree
          where
            setibalance a = a{aibalance=
              fromMaybe 0 $ -- when there's no actual amount, assume 0; will mess up with negative amounts ? TODO 
              fromMaybe (error "sortTreeByAmount 1") $ -- should not happen, but it's ugly; TODO 
              lookup (aname a) atotals
              }
        sortedaccounttree = sortAccountTreeByAmount (fromMaybe NormallyPositive $ normalbalance_ ropts) accounttreewithbals
        sortedanames = map aname $ drop 1 $ flattenAccounts sortedaccounttree
        sortedrows = sortAccountItemsLike sortedanames anamesandrows 

    -- Sort a flat-mode budget report's rows by total actual amount.
    sortFlatBURByActualAmount :: [BudgetReportRow] -> [BudgetReportRow] 
    sortFlatBURByActualAmount = sortBy (maybeflip $ comparing (fst . fifth6))
      where
        maybeflip = if normalbalance_ ropts == Just NormallyNegative then id else flip

    -- Sort the report rows by account declaration order then account name. 
    -- <unbudgeted> remains at the top.
    sortByAccountDeclaration rows = sortedrows
      where
        (unbudgetedrow,rows') = partition ((=="<unbudgeted>").first6) rows
        anamesandrows = [(first6 r, r) | r <- rows']
        anames = map fst anamesandrows
        sortedanames = sortAccountNamesByDeclaration j (tree_ ropts) anames
        sortedrows = unbudgetedrow ++ sortAccountItemsLike sortedanames anamesandrows 

-- | Use all periodic transactions in the journal to generate 
-- budget transactions in the specified report period.
-- Budget transactions are similar to forecast transactions except
-- their purpose is to set goal amounts (of change) per account and period.
budgetJournal :: Bool -> ReportOpts -> DateSpan -> Journal -> Journal
budgetJournal assrt _ropts reportspan j =
  either error' id $ journalBalanceTransactions assrt j{ jtxns = budgetts }
  where
    budgetspan = dbg2 "budgetspan" $ reportspan
    budgetts =
      dbg1 "budgetts" $
      [makeBudgetTxn t
      | pt <- jperiodictxns j
      , t <- runPeriodicTransaction pt budgetspan
      ]
    makeBudgetTxn t = txnTieKnot $ t { tdescription = T.pack "Budget transaction" }

-- | Adjust a journal's account names for budget reporting, in two ways:
--
-- 1. accounts with no budget goal anywhere in their ancestry are moved 
--    under the "unbudgeted" top level account.
--
-- 2. subaccounts with no budget goal are merged with their closest parent account
--    with a budget goal, so that only budgeted accounts are shown. 
--    This can be disabled by --show-unbudgeted.
--
budgetRollUp :: [AccountName] -> Bool -> Journal -> Journal
budgetRollUp budgetedaccts showunbudgeted j = j { jtxns = remapTxn <$> jtxns j }
  where
    remapTxn = mapPostings (map remapPosting)
      where
        mapPostings f t = txnTieKnot $ t { tpostings = f $ tpostings t }
        remapPosting p = p { paccount = remapAccount $ paccount p, porigin = Just . fromMaybe p $ porigin p }
          where
            remapAccount a
              | hasbudget         = a
              | hasbudgetedparent = if showunbudgeted then a else budgetedparent 
              | otherwise         = if showunbudgeted then u <> acctsep <> a else u
              where
                hasbudget = a `elem` budgetedaccts
                hasbudgetedparent = not $ T.null budgetedparent
                budgetedparent = headDef "" $ filter (`elem` budgetedaccts) $ parentAccountNames a
                u = unbudgetedAccountName

-- | Combine a per-account-and-subperiod report of budget goals, and one
-- of actual change amounts, into a budget performance report.
-- The two reports should have the same report interval, but need not
-- have exactly the same account rows or date columns.
-- (Cells in the combined budget report can be missing a budget goal,
-- an actual amount, or both.) The combined report will include:
--
-- - consecutive subperiods at the same interval as the two reports,
--   spanning the period of both reports
--
-- - all accounts mentioned in either report, sorted by account code or
--   account name or amount as appropriate.
--
combineBudgetAndActual :: MultiBalanceReport -> MultiBalanceReport -> BudgetReport
combineBudgetAndActual
  (MultiBalanceReport (budgetperiods, budgetrows, (budgettots, budgetgrandtot, budgetgrandavg)))
  (MultiBalanceReport (actualperiods, actualrows, (actualtots, actualgrandtot, actualgrandavg))) =
  let
    periods = nub $ sort $ filter (/= nulldatespan) $ budgetperiods ++ actualperiods

    -- first, combine any corresponding budget goals with actual changes
    rows1 =
      [ (acct, treeacct, treeindent, amtandgoals, totamtandgoal, avgamtandgoal)
      | (acct, treeacct, treeindent, actualamts, actualtot, actualavg) <- actualrows
      , let mbudgetgoals       = Map.lookup acct budgetGoalsByAcct :: Maybe ([BudgetGoal], BudgetTotal, BudgetAverage)
      , let budgetmamts        = maybe (replicate (length periods) Nothing) (map Just . first3) mbudgetgoals :: [Maybe BudgetGoal]
      , let mbudgettot         = maybe Nothing (Just . second3) mbudgetgoals :: Maybe BudgetTotal
      , let mbudgetavg         = maybe Nothing (Just . third3)  mbudgetgoals :: Maybe BudgetAverage
      , let acctBudgetByPeriod = Map.fromList [ (p,budgetamt) | (p, Just budgetamt) <- zip budgetperiods budgetmamts ] :: Map DateSpan BudgetGoal
      , let acctActualByPeriod = Map.fromList [ (p,actualamt) | (p, Just actualamt) <- zip actualperiods (map Just actualamts) ] :: Map DateSpan Change
      , let amtandgoals        = [ (Map.lookup p acctActualByPeriod, Map.lookup p acctBudgetByPeriod) | p <- periods ] :: [(Maybe Change, Maybe BudgetGoal)]
      , let totamtandgoal      = (Just actualtot, mbudgettot)
      , let avgamtandgoal      = (Just actualavg, mbudgetavg)
      ]
      where
        budgetGoalsByAcct :: Map AccountName ([BudgetGoal], BudgetTotal, BudgetAverage) =
          Map.fromList [ (acct, (amts, tot, avg)) | (acct, _, _, amts, tot, avg) <- budgetrows ]

    -- next, make rows for budget goals with no actual changes
    rows2 =
      [ (acct, treeacct, treeindent, amtandgoals, totamtandgoal, avgamtandgoal)
      | (acct, treeacct, treeindent, budgetgoals, budgettot, budgetavg) <- budgetrows
      , not $ acct `elem` acctsdone
      , let acctBudgetByPeriod = Map.fromList $ zip budgetperiods budgetgoals :: Map DateSpan BudgetGoal
      , let amtandgoals        = [ (Nothing, Map.lookup p acctBudgetByPeriod) | p <- periods ] :: [(Maybe Change, Maybe BudgetGoal)]
      , let totamtandgoal      = (Nothing, Just budgettot)
      , let avgamtandgoal      = (Nothing, Just budgetavg)
      ]
      where
        acctsdone = map first6 rows1

    -- combine and re-sort rows
    -- TODO: use MBR code
    -- TODO: respect --sort-amount
    -- TODO: add --sort-budget to sort by budget goal amount
    rows :: [PeriodicReportRow (Maybe Change, Maybe BudgetGoal)] =
      sortBy (comparing first6) $ rows1 ++ rows2

    -- TODO: grand total & average shows 0% when there are no actual amounts, inconsistent with other cells
    totalrow =
      ( ""
      , ""
      , 0
      , [ (Map.lookup p totActualByPeriod, Map.lookup p totBudgetByPeriod) | p <- periods ] :: [(Maybe Total, Maybe BudgetTotal)]
      , ( Just actualgrandtot, Just budgetgrandtot ) :: (Maybe Total, Maybe BudgetTotal)
      , ( Just actualgrandavg, Just budgetgrandavg ) :: (Maybe Total, Maybe BudgetTotal)
      )
      where
        totBudgetByPeriod = Map.fromList $ zip budgetperiods budgettots :: Map DateSpan BudgetTotal
        totActualByPeriod = Map.fromList $ zip actualperiods actualtots :: Map DateSpan Change

  in
    PeriodicReport
      ( periods
      , rows
      , totalrow
      )

-- | Figure out the overall period of a BudgetReport.
budgetReportSpan :: BudgetReport -> DateSpan
budgetReportSpan (PeriodicReport ([], _, _))    = DateSpan Nothing Nothing
budgetReportSpan (PeriodicReport (spans, _, _)) = DateSpan (spanStart $ head spans) (spanEnd $ last spans)

-- | Render a budget report as plain text suitable for console output.
budgetReportAsText :: ReportOpts -> BudgetReport -> String
budgetReportAsText ropts budgetr =
  printf "Budget performance in %s:\n\n" (showDateSpan $ budgetReportSpan budgetr)
  ++ 
  tableAsText ropts showcell (budgetReportAsTable ropts budgetr)
  where
    -- XXX lay out actual, percentage and/or goal in the single table cell for now, should probably use separate cells
    showcell :: (Maybe Change, Maybe BudgetGoal) -> String
    showcell (mactual, mbudget) = actualstr ++ " " ++ budgetstr
      where
        actualwidth  = 7
        percentwidth = 4
        budgetwidth  = 5
        actual = fromMaybe 0 mactual
        actualstr = printf ("%"++show actualwidth++"s") (showamt actual)
        budgetstr = case mbudget of
          Nothing     -> replicate (percentwidth + 7 + budgetwidth) ' '
          Just budget ->
            case percentage actual budget of
              Just pct ->
                printf ("[%"++show percentwidth++"s%% of %"++show budgetwidth++"s]")
                       (show $ roundTo 0 pct) (showbudgetamt budget)
              Nothing ->
                printf ("["++replicate (percentwidth+5) ' '++"%"++show budgetwidth++"s]")
                       (showbudgetamt budget)

    -- | Calculate the percentage of actual change to budget goal to show, if any.
    -- Both amounts are converted to cost, if possible, before comparing.
    -- A percentage will not be shown if:
    -- - actual or goal are not the same, single, commodity
    -- - the goal is zero
    percentage :: Change -> BudgetGoal -> Maybe Percentage
    percentage actual budget =
      case (toCost actual, toCost budget) of
        (Mixed [a], Mixed [b]) | (acommodity a == acommodity b || isZeroAmount a) && not (isZeroAmount b) 
            -> Just $ 100 * aquantity a / aquantity b
        _   -> Nothing
      where
        toCost = normaliseMixedAmount . costOfMixedAmount 

    showamt :: MixedAmount -> String
    showamt | color_ ropts  = cshowMixedAmountOneLineWithoutPrice
            | otherwise     = showMixedAmountOneLineWithoutPrice

    -- don't show the budget amount in color, it messes up alignment
    showbudgetamt = showMixedAmountOneLineWithoutPrice

-- | Build a 'Table' from a multi-column balance report.
budgetReportAsTable :: ReportOpts -> BudgetReport -> Table String String (Maybe MixedAmount, Maybe MixedAmount)
budgetReportAsTable 
  ropts 
  (PeriodicReport
    ( periods
    , rows
    , (_, _, _, coltots, grandtot, grandavg)
    )) =
    addtotalrow $ 
    Table
      (T.Group NoLine $ map Header accts)
      (T.Group NoLine $ map Header colheadings)
      (map rowvals rows)
  where
    colheadings = map showDateSpanMonthAbbrev periods
                  ++ (if row_total_ ropts then ["  Total"] else [])
                  ++ (if average_   ropts then ["Average"] else [])
    accts = map renderacct rows
    renderacct (a,a',i,_,_,_)
      | tree_ ropts = replicate ((i-1)*2) ' ' ++ T.unpack a'
      | otherwise   = T.unpack $ maybeAccountNameDrop ropts a
    rowvals (_,_,_,as,rowtot,rowavg) = as
                                       ++ (if row_total_ ropts then [rowtot] else [])
                                       ++ (if average_   ropts then [rowavg] else [])
    addtotalrow | no_total_ ropts = id
                | otherwise       = (+----+ (row "" $
                                     coltots
                                     ++ (if row_total_ ropts && not (null coltots) then [grandtot] else [])
                                     ++ (if average_   ropts && not (null coltots) then [grandavg] else [])
                                     ))

-- XXX here for now
-- TODO: does not work for flat-by-default reports with --flat not specified explicitly  
-- | Drop leading components of accounts names as specified by --drop, but only in --flat mode.
maybeAccountNameDrop :: ReportOpts -> AccountName -> AccountName
maybeAccountNameDrop opts a | flat_ opts = accountNameDrop (drop_ opts) a
                            | otherwise  = a

-- tests

tests_BudgetReport = tests "BudgetReport" [
 ]
