type ModuleName = String
type Version    = String
type ModuleId   = Int
type UserName   = String
type Timestamp  = Int

type Module     = (ModuleId, ModuleName, Version)

type Dependency = (ModuleId, ModuleId)

type Usage      = (ModuleId, UserName, Timestamp)

type Database   = ([Module], [Dependency], [Usage])

-- Gettery
getModuleId :: Module -> ModuleId
getModuleId = undefined

getModuleName :: Module -> ModuleName
getModuleName  = undefined

getVersion :: Module -> Version
getVersion = undefined

getUsageMId :: Usage -> ModuleId
getUsageMId = undefined

getTimestamp :: Usage -> Timestamp
getTimestamp = undefined

getUser :: Usage -> UserName
getUser = undefined

-- Funkce pracující s databází
moduleInfo :: ModuleId -> [Module] -> (ModuleName, Version)
moduleInfo = undefined

moduleId :: ModuleName -> Version -> [Module] -> ModuleId
moduleId = undefined

versionsOf :: ModuleName -> [Module] -> [(ModuleId, Version)]
versionsOf = undefined

lastUsedModule :: [Usage] -> ModuleId
lastUsedModule = undefined

lastUserOf :: ModuleId -> [Usage] -> UserName
lastUserOf = undefined

insertUsage :: ModuleId -> UserName -> Timestamp
            -> [Usage] -> [Usage]
insertUsage = undefined

dependenciesOf :: ModuleId -> [Dependency] -> [ModuleId]
dependenciesOf = undefined

dependingOn :: ModuleId -> [Dependency] -> [ModuleId]
dependingOn = undefined

activeSince :: Timestamp -> Database -> [ModuleId]
activeSince = undefined

purgeModule :: ModuleId -> Database -> Database
purgeModule = undefined


-------------------------------------------------------------------------------
--                     S A M P L E    D A T A B A S E                        --
-------------------------------------------------------------------------------


testDB :: Database
testDB = (testModules, testDependencies, testUsage)

testModules :: [Module]
testModules = [ (1, "ghc", "9.0.1"), (2, "xmobar", "0.35.1"), (3, "ghc", "8.4.3")
              , (42, "gcc", "10.3.0"), (66, "git", "2.25.1"), (100, "libc", "2.31")
              , (5, "perl", "5.24") ]

testDependencies :: [Dependency]
testDependencies = [ (2, 1), (100, 42), (66, 42), (66, 5) ]

testUsage :: [Usage]
testUsage = [ (1, "Simon Marlow", 1631009291), (5, "Larry Wall", 1464048000)
            , (2, "Gary Fuchs", 1580443221), (3, "Linus O'Reilly", 1493401234)
            , (5, "Garry Fuchs", 1323491235) ]