{-# LANGUAGE UnicodeSyntax #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE TemplateHaskell #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}

-- |
-- Module      :  HBooru.Types
-- Copyright   :  (c) Mateusz Kowalczyk 2013-2014
-- License     :  GPL-3
--
-- Maintainer  :  fuuzetsu@fuuzetsu.co.uk
-- Stability   :  experimental
--
-- Module definining types used by the library.
module HBooru.Types where

import Data.Proxy
import GHC.TypeLits (Symbol)
import Data.Vinyl
import Data.Vinyl.TH
import Prelude hiding (id)
import Text.XML.HXT.Core hiding (mkName, (<+>))

-- | Tags used for searching in sites. No special escaping is done.
-- Note that many sites would treat a tag like \"striped panties\"
-- as two separate tags and you wouldn't get the results you were after.
type Tag = String

-- | Data format used by various 'Site's. See instances for currently used
-- formats.
class DataFormat a where

-- | Used as one of the data formats.
data XML = XML deriving Show

-- | Used as one of the data formats.
data JSON = JSON deriving Show

instance DataFormat XML where
instance DataFormat JSON where

-- | Thanks to this class, we're able to provide instances converting
-- from a 'DataFormat' to 'Response'. This is useful if we need a 'DataFormat'
-- while we only have a type that's an instance of 'Response'. Note that the
-- functional dependency currently requires that there is only one way to coerce
-- between two types.
class Response r ⇒ CoerceResponse x r | x → r, r → x where
  -- | Given something and a 'String', we get the appropriate 'Response'.
  -- For example with @instance 'CoerceResponse' 'XML' 'XMLResponse'@:
  --
  -- >>> toResponse XML "<SomeXML></SomeXML>"
  -- XMLReponse "<SomeXML></SomeXML>"
  toResponse ∷ x → String → r
  -- | Given some kind of 'Response', we get the appropriate value back,
  -- depending on the class instance.
  -- For example with @instance 'CoerceResponse' 'XML' 'XMLResponse'@:
  --
  -- >>> fromResponse $ XMLReponse "<SomeXML></SomeXML>"
  -- XML
  fromResponse ∷ r → x

instance CoerceResponse XML XMLResponse where
  toResponse _ = XMLResponse
  fromResponse _ = XML

instance CoerceResponse JSON JSONResponse where
  toResponse _ = JSONResponse
  fromResponse _ = JSON

-- | Class specifying a parser that can fetch posts. A post usually
-- consists of links to the image, samples, and some meta-data. The
-- reason for this class is that sometimes we might get different
-- information based on the 'DataFormat' we use so we use type
-- families to denote this rather than forcing the library user to
-- make do with our best guess on what goes into the post. It also
-- allows us to use different post types for sites that provide
-- different information.
class (Site s, DataFormat r) ⇒ PostParser s r where
  type ImageTy s r
  -- | Given a parser working with 'DataFormat' specified by an instance of
  -- this class, we require through 'CoerceResponse' that it is able to parse
  -- responses in the format so what we actually pass into this function is
  -- the 'Site' this parser works with (so that we can pick the appropriate data
  -- type for the posts) and a 'Response' matching the 'DataFormat' (through a
  -- class instance). For @PostParser 'Gelbooru' 'XML'@ instance, example use
  -- might go like
  --
  -- @
  -- do fc \<- 'XMLResponse' <$> 'readFile' \"gelbooruResponse.xml\"
  --    -- the type of images is actually inferred for us
  --    let images ∷ ['HBooru.Parsers.Gelbooru.GelbooruPost']
  --        images = parseResponse 'HBooru.Parsers.Gelbooru.Gelbooru' fc
  --    return images
  -- @
  --
  -- The cool thing is that we can't feed anything but 'XMLResponse' to an
  -- XML parser.
  parseResponse ∷ CoerceResponse r r' ⇒ s → r' → [ImageTy s r]

-- | Describes whether a response from a 'Site' in given 'DataFormat'
-- allows us to get the information about total number of posts matching our
-- query. Some sites don't provide this information.
class (Site s, DataFormat r) ⇒ Counted s r where
  -- | Parses out the number of available images from a response.
  parseCount ∷ CoerceResponse r r' ⇒ s → r' → Integer

class (Counted s r, Postable s r) ⇒ PostablePaged s r where
  -- | Similar to 'postUrl' but requests images from specific page if
  -- the site allows it.
  postUrlPaged ∷ s → r → [Tag] → Integer → String
  postUrlPaged s r ts i = postUrl s r ts ++ "&pid=" ++ show i

-- | If we can make an API request to 'Site' in a specific 'DataFormat', we can
-- use instances of this class to pass in
class PostParser s r ⇒ Postable s r where
  -- | Given a 'Site', a 'DataFormat' and a list of 'Tag's, an instance of this
  -- class should be able to return a 'String' at which we can find data in
  -- 'DataFormat' format that honours our tags. This is effectively a URL
  -- builder for POST requests.
  postUrl ∷ s → r → [Tag] → String
  -- | Provides information about whether there's a hard limit on the amount of
  -- posts we can fetch from the site at once. The reason for this function here
  -- rather than in 'Site' is that we might be parsing data without an API we
  -- can post to at all and we're getting our data through other means.
  hardLimit ∷ s → r → Limit

-- | Describes a site for a parser. The reason why this isn't a simple data type
-- is to allow us to write additional parsers in the future without modifying
-- this library if we wish to do so.
class Site s where

-- | Rating used on *booru sites.
data Rating = Safe | Questionable | Explicit deriving (Show, Eq)

-- | Denotes whethere there's a hard limit on the number of posts
-- we can fetch at a time from a site. NoLimit implies that we can fetch
-- everything at once and not that we don't know. See 'Counted' for a way to
-- potentially retrieve number of posts present on the site.
data Limit = NoLimit | Limit Integer deriving (Show, Eq)

-- | One of the formats we can receive responses from sites in. For things
-- like parsers parametrisation, use 'XML' instead and use methods in
-- 'CoerceResponse' if you need to.
data XMLResponse = XMLResponse String deriving Show

-- | One of the formats we can receive responses from sites in. For things
-- like parsers parametrisation, use 'JSON' instead and use methods in
-- 'CoerceResponse' if you need to.
data JSONResponse = JSONResponse String deriving Show

-- | Specifies what is considered a response. You'll almost certainly also
-- want new 'DataFormat' and 'CoerceResponse' instances if you're adding some
-- here. This class assumes that all responses carry the response in a string we
-- can extract. Note that this is not for use as network response if you're
-- scraping, only for putting data into after you have done all the error
-- checking and whatnot.
class Response r where
  -- | Extract the response string.
  getResponse ∷ r → String

instance Response XMLResponse where
  getResponse (XMLResponse x) = x

instance Response JSONResponse where
  getResponse (JSONResponse x) = x


instance Functor (LA XmlTree) where
  fmap f (LA g) = LA $ fmap fmap fmap f g

makeUniverse' ''Symbol "ElF"
semantics ''ElF [ [t| "height" |]                :~> [t| Integer |]
                , [t| "score" |]                 :~> [t| Integer |]
                , [t| "file_url" |]              :~> [t| String |]
                , [t| "parent_id" |]             :~> [t| Maybe Integer |]
                , [t| "sample_url" |]            :~> [t| String |]
                , [t| "sample_width" |]          :~> [t| Integer |]
                , [t| "sample_height" |]         :~> [t| Integer |]
                , [t| "preview_url" |]           :~> [t| String |]
                , [t| "rating" |]                :~> [t| Rating |]
                , [t| "tags" |]                  :~> [t| [Tag] |]
                , [t| "id" |]                    :~> [t| Integer |]
                , [t| "width" |]                 :~> [t| String |]
                , [t| "change" |]                :~> [t| String |]
                , [t| "md5" |]                   :~> [t| String |]
                , [t| "creator_id" |]            :~> [t| Integer |]
                , [t| "has_children" |]          :~> [t| Bool |]
                , [t| "created_at" |]            :~> [t| String |]
                , [t| "status" |]                :~> [t| String |]
                , [t| "source" |]                :~> [t| String |]
                , [t| "has_notes" |]             :~> [t| Maybe Bool |]
                , [t| "has_comments" |]          :~> [t| Maybe Bool |]
                , [t| "preview_width" |]         :~> [t| Integer |]
                , [t| "preview_height" |]        :~> [t| Integer |]
                , [t| "author" |]                :~> [t| String |]
                , [t| "frames" |]                :~> [t| String |]
                , [t| "frames_pending" |]        :~> [t| String |]
                , [t| "frames_pending_string" |] :~> [t| String |]
                , [t| "frames_string" |]         :~> [t| String |]
                , [t| "is_held" |]               :~> [t| Bool |]
                , [t| "is_shown_in_index" |]     :~> [t| Bool |]
                , [t| "jpeg_file_size" |]        :~> [t| Integer |]
                , [t| "jpeg_height" |]           :~> [t| Integer |]
                , [t| "jpeg_url" |]              :~> [t| String |]
                , [t| "jpeg_width" |]            :~> [t| Integer |]
                , [t| "sample_file_size" |]      :~> [t| Integer |]
                , [t| "actual_preview_height" |] :~> [t| Integer |]
                , [t| "actual_preview_width" |]  :~> [t| Integer |]
                , [t| "file_size" |]             :~> [t| Integer |]
                ]

-- | Handy synonym hiding 'ElF'.
type R a = PlainRec ElF a

-- * Commonly used fields

height ∷ Proxy "height"
height = Proxy

score ∷ Proxy "score"
score = Proxy

file_url ∷ Proxy "file_url"
file_url = Proxy

parent_id ∷ Proxy "parent_id"
parent_id = Proxy

sample_url ∷ Proxy "sample_url"
sample_url = Proxy

sample_width ∷ Proxy "sample_width"
sample_width = Proxy

sample_height ∷ Proxy "sample_height"
sample_height = Proxy

preview_url ∷ Proxy "preview_url"
preview_url = Proxy

rating ∷ Proxy "rating"
rating = Proxy

tags ∷ Proxy "tags"
tags = Proxy

id ∷ Proxy "id"
id = Proxy

width ∷ Proxy "width"
width = Proxy

change ∷ Proxy "change"
change = Proxy

md5 ∷ Proxy "md5"
md5 = Proxy

creator_id ∷ Proxy "creator_id"
creator_id = Proxy

has_children ∷ Proxy "has_children"
has_children = Proxy

created_at ∷ Proxy "created_at"
created_at = Proxy

status ∷ Proxy "status"
status = Proxy

source ∷ Proxy "source"
source = Proxy

has_notes ∷ Proxy "has_notes"
has_notes = Proxy

has_comments ∷ Proxy "has_comments"
has_comments = Proxy

preview_width ∷ Proxy "preview_width"
preview_width = Proxy

preview_height ∷ Proxy "preview_height"
preview_height = Proxy

author ∷ Proxy "author"
author = Proxy

frames ∷ Proxy "frames"
frames = Proxy

frames_pending ∷ Proxy "frames_pending"
frames_pending = Proxy

frames_pending_string ∷ Proxy "frames_pending_string"
frames_pending_string = Proxy

frames_string ∷ Proxy "frames_string"
frames_string = Proxy

is_held ∷ Proxy "is_held"
is_held = Proxy

is_shown_in_index ∷ Proxy "is_shown_in_index"
is_shown_in_index = Proxy

jpeg_file_size ∷ Proxy "jpeg_file_size"
jpeg_file_size = Proxy

jpeg_height ∷ Proxy "jpeg_height"
jpeg_height = Proxy

jpeg_url ∷ Proxy "jpeg_url"
jpeg_url = Proxy

jpeg_width ∷ Proxy "jpeg_width"
jpeg_width = Proxy

sample_file_size ∷ Proxy "sample_file_size"
sample_file_size = Proxy

actual_preview_height ∷ Proxy "actual_preview_height"
actual_preview_height = Proxy

actual_preview_width ∷ Proxy "actual_preview_width"
actual_preview_width = Proxy

file_size ∷ Proxy "file_size"
file_size = Proxy