import Data.Maybe

cao_20_7_4 = (*1.15)
kg_to_lb = (*2.2)
ft_to_metre = (*0.3048)
litre_to_kg_avgas = (*0.72)
taxi_fuel_kg = 5
modrem x d = fromInteger (x `mod` d) / fromInteger d

-- Calculate pressure altitude

isatemp = 15
isapressure = 1013.25
pressure_altitude ele qnh = max 0 (fromIntegral ele + (isapressure - fromIntegral qnh) * 30)
declared_temp da = isatemp - da / 500

-- Find the 4 numbers to interpolate
--     nw     ne
--     sw     se
-- Calculate the proportion of the temperature to interpolate (0 >= temp_prop <= 1)
-- Calculate the proportion of the pressure altutide to interpolate (0 >= pa_prop <= 1)

data DistanceRequired =
  DistanceRequired {
    distance_required_ft
      :: Double
  , distance_required_ft_cao20_7_4
      :: Double
  , distance_required_metre
      :: Double
  , distance_required_metre_cao20_7_4
      :: Double
 } deriving (Eq, Show)

f <<$>> DistanceRequired nw sw ne se =
  DistanceRequired (f nw) (f sw) (f ne) (f se)

eachDistanceRequired f (DistanceRequired nw1 sw1 ne1 se1) (DistanceRequired nw2 sw2 ne2 se2) =
  DistanceRequired (f nw1 nw2) (f sw1 sw2) (f ne1 ne2) (f se1 se2)

distanceRequired1 x =
  DistanceRequired x (cao_20_7_4 x) (ft_to_metre x) (cao_20_7_4 (ft_to_metre x))

grass gr clear50ft =
  let gr' = (*1.45) <<$>> gr
      t = eachDistanceRequired (+) (eachDistanceRequired (-) clear50ft gr) gr'
  in  (gr', t)

interpolate ::
  Double
  -> Double
  -> Double
  -> Double
  -> Double
  -> Double
  -> DistanceRequired
interpolate nw sw ne se da temp =
  let temp_prop = modrem (round temp) 10
      interpolate' a b prop = (a-b)*prop+b
      interpolate_temp a b = interpolate' a b temp_prop
      result = interpolate' (interpolate_temp se sw) (interpolate_temp ne nw) (modrem (round da) 1000)
  in distanceRequired1 result

data Check a =
  Check a a
  deriving (Eq, Ord, Show)

(===) ::
  a
  -> a
  -> Check a
(===) =
  Check

infixl 4 ===

v ::
  Check a
  -> a
v (Check a _) =
  a

check ::
  (Show a, Eq a) =>
  Check a
  -> Maybe String
check (Check a1 a2) =
  if a1 == a2
    then Nothing
    else Just (concat [show a1, " /= ", show a2])

----

---- YBAF

ybaf_declared_density = 2400 -- ft
ybaf_ele = 65 -- ft
ybaf_declared_density_height = ybaf_declared_density + ybaf_ele === 2465
ybaf_declared_temp = declared_temp (v ybaf_declared_density_height) === 10.07
ybaf_interpolate nw sw ne se = interpolate nw sw ne se (v ybaf_declared_density_height) (v ybaf_declared_temp)

---- YRED

yred_declared_density = 2400 -- ft
yred_ele = 7 -- ft
yred_declared_density_height = yred_declared_density + yred_ele === 2407
yred_declared_temp = declared_temp (v yred_declared_density_height) === 10.186
yred_interpolate nw sw ne se = interpolate nw sw ne se (v yred_declared_density_height) (v yred_declared_temp)

---- YBSU

ybsu_declared_density = 2400 -- ft
ybsu_ele = 15 -- ft
ybsu_declared_density_height = ybsu_declared_density + ybsu_ele === 2415
ybsu_declared_temp = declared_temp (v ybsu_declared_density_height) === 10.17
ybsu_interpolate nw sw ne se = interpolate nw sw ne se (v ybsu_declared_density_height) (v ybsu_declared_temp)

---- YTWB

ytwb_declared_density = 2500 -- ft
ytwb_ele = 2086 -- ft
ytwb_declared_density_height = ytwb_declared_density + ytwb_ele === 4586
ytwb_declared_temp = declared_temp (v ytwb_declared_density_height) === 5.827999999999999
ytwb_interpolate nw sw ne se = interpolate nw sw ne se (v ytwb_declared_density_height) (v ytwb_declared_temp)

----

-- TODR YBAF
-- *2400lb*

todr_ybaf_groundroll = ybaf_interpolate 1035 1140 2060 2295 ===
  DistanceRequired {
    distance_required_ft = 1083.825
  , distance_required_ft_cao20_7_4 = 1246.39875
  , distance_required_metre = 330.34986000000004
  , distance_required_metre_cao20_7_4 = 379.902339
  }

todr_ybaf_50ft = ybaf_interpolate 1910 2120 2060 2295 ===
  DistanceRequired {
    distance_required_ft = 2007.65
  , distance_required_ft_cao20_7_4 = 2308.7975
  , distance_required_metre = 611.93172
  , distance_required_metre_cao20_7_4 = 703.721478
  }

-- LDR YRED
-- *2400lb*

ldr_yred_groundroll = yred_interpolate 570 590 590 615 ===
  DistanceRequired {
    distance_required_ft = 578.14
  , distance_required_ft_cao20_7_4 = 664.8609999999999
  , distance_required_metre = 176.217072
  , distance_required_metre_cao20_7_4 = 202.64963279999998
  }

ldr_yred_50ft = ybsu_interpolate 1330 1360 1360 1395 ===
  DistanceRequired {
    distance_required_ft = 1342.45
  , distance_required_ft_cao20_7_4 = 1543.8174999999999
  , distance_required_metre = 409.17876
  , distance_required_metre_cao20_7_4 = 470.555574
  }

-- TODR YRED
-- *2400lb*

todr_yred_groundroll = yred_interpolate 1035 1140 2060 2295 ===
  DistanceRequired {
    distance_required_ft = 1077.735
  , distance_required_ft_cao20_7_4 = 1239.3952499999998
  , distance_required_metre = 328.493628
  , distance_required_metre_cao20_7_4 = 377.7676722
  }

todr_yred_50ft = yred_interpolate 1910 2120 2060 2295 ===
  DistanceRequired {
    distance_required_ft = 1995.47
  , distance_required_ft_cao20_7_4 = 2294.7905
  , distance_required_metre = 608.2192560000001
  , distance_required_metre_cao20_7_4 = 699.4521444000001
  }

-- LDR YBSU
-- *2400lb*

ldr_ybsu_groundroll = ybsu_interpolate 570 590 590 615 ===
  DistanceRequired {
    distance_required_ft = 578.3
  , distance_required_ft_cao20_7_4 = 665.0449999999998
  , distance_required_metre = 176.26584
  , distance_required_metre_cao20_7_4 = 202.70571599999997
  }

ldr_ybsu_50ft = ybsu_interpolate 1330 1360 1360 1395 ===
  DistanceRequired {
    distance_required_ft = 1342.45
  , distance_required_ft_cao20_7_4 = 1543.8174999999999
  , distance_required_metre = 409.17876
  , distance_required_metre_cao20_7_4 = 470.555574
  }

-- TODR YBSU
-- *2400lb*

todr_ybsu_groundroll = ybsu_interpolate 1035 1140 2060 2295 ===
  DistanceRequired {
    distance_required_ft = 1078.575
  , distance_required_ft_cao20_7_4 = 1240.36125
  , distance_required_metre = 328.74966
  , distance_required_metre_cao20_7_4 = 378.06210899999996
  }

todr_ybsu_50ft = ybsu_interpolate 1910 2120 2060 2295 ===
  DistanceRequired {
    distance_required_ft = 1997.15
  , distance_required_ft_cao20_7_4 = 2296.7225
  , distance_required_metre = 608.7313200000001
  , distance_required_metre_cao20_7_4 = 700.041018
  }

-- LDR YTWB
-- *2400lb*

ldr_ytwb_groundroll = ytwb_interpolate 595 615 615 640 ===
  DistanceRequired {
    distance_required_ft = 620.478
  , distance_required_ft_cao20_7_4 = 713.5496999999999
  , distance_required_metre = 189.1216944
  , distance_required_metre_cao20_7_4 = 217.48994856
  }

ldr_ytwb_50ft = ytwb_interpolate 1365 1400 1400 1435 ===
  DistanceRequired {
    distance_required_ft = 1406.51
  , distance_required_ft_cao20_7_4 = 1617.4865
  , distance_required_metre = 428.704248
  , distance_required_metre_cao20_7_4 = 493.0098852
  }

-- TODR YTWB
-- *2400lb*

todr_ytwb_groundroll = ytwb_interpolate 1165 1285 1260 1390 ===
  DistanceRequired {
    distance_required_ft = 1295.836
  , distance_required_ft_cao20_7_4 = 1490.2114
  , distance_required_metre = 394.97081280000003
  , distance_required_metre_cao20_7_4 = 454.21643472
  }

todr_ytwb_50ft = ytwb_interpolate 2165 2445 2365 2660 ===
  DistanceRequired {
    distance_required_ft = 2454.354
  , distance_required_ft_cao20_7_4 = 2822.5070999999994
  , distance_required_metre = 748.0870992
  , distance_required_metre_cao20_7_4 = 860.30016408
  }

-- LDR YBAF
-- *2400lb*

ldr_ybaf_groundroll = ybaf_interpolate 550 570 570 590 ===
  DistanceRequired {
    distance_required_ft = 559.3
  , distance_required_ft_cao20_7_4 = 643.1949999999999
  , distance_required_metre = 170.47464
  , distance_required_metre_cao20_7_4 = 196.04583599999998
  }

ldr_ybaf_50ft = ybaf_interpolate 1295 1330 1330 1360 ===
  DistanceRequired {
    distance_required_ft = 1311.275
  , distance_required_ft_cao20_7_4 = 1507.96625
  , distance_required_metre = 399.67662000000007
  , distance_required_metre_cao20_7_4 = 459.62811300000004
  }

----

ybaf_checks =
  [
    ybaf_declared_density_height
  , ybaf_declared_temp
  ]

ybsu_checks =
  [
    ybsu_declared_density_height
  , ybsu_declared_temp
  ]

ytwb_checks =
  [
    ytwb_declared_density_height
  , ytwb_declared_temp
  ]

todr_ybaf_checks =
  [
    todr_ybaf_groundroll
  , todr_ybaf_50ft
  ]

ldr_yred_checks =
  [
    ldr_yred_groundroll
  , ldr_yred_50ft
  ]

todr_yred_checks =
  [
    todr_yred_groundroll
  , todr_yred_50ft
  ]
  
yred_checks =
  concat
    [
      [
        yred_declared_density_height
      , yred_declared_temp
      ]
    ]

ldr_ybsu_checks =
  [
    ldr_ybsu_groundroll
  , ldr_ybsu_50ft
  ]

todr_ybsu_checks =
  [
    todr_ybsu_groundroll
  , todr_ybsu_50ft
  ]

ldr_ytwb_checks =
  [
    ldr_ytwb_groundroll
  , ldr_ytwb_50ft
  ]

todr_ytwb_checks =
  [
    todr_ytwb_groundroll
  , todr_ytwb_50ft
  ]
  
ldr_ybaf_checks =
  [
    ldr_ybaf_groundroll
  , ldr_ybaf_50ft
  ]

checks =
  concat
    [
      ybaf_checks
    , yred_checks
    , ybsu_checks
    , ytwb_checks
    ]

todr_checks =
  concat
    [
      todr_ybaf_checks
    , todr_yred_checks
    , todr_ybsu_checks
    , todr_ytwb_checks
    ]

ldr_checks =
  concat
    [
      ldr_ybsu_checks
    , ldr_yred_checks
    , ldr_ytwb_checks
    , ldr_ybaf_checks
    ]

all_checks =
  map check checks ++
  map check todr_checks ++
  map check ldr_checks

failed_checks =
  catMaybes all_checks