#
#
#            Nim's Runtime Library
#        (c) Copyright 2015 Dominik Picheta
#
#    See the file "copying.txt", included in this
#    distribution, for details about the copyright.
#

## This module implements URI parsing as specified by RFC 3986.

import strutils, parseutils
type
  Url* = distinct string

  Uri* = object
    scheme*, username*, password*: string
    hostname*, port*, path*, query*, anchor*: string
    opaque*: bool

{.push warning[deprecated]: off.}
proc `$`*(url: Url): string {.deprecated: "use Uri instead".} =
  ## **Deprecated since 0.9.6**: Use ``Uri`` instead.
  return string(url)

proc `/`*(a, b: Url): Url {.deprecated: "use Uri instead".} =
  ## Joins two URLs together, separating them with / if needed.
  ##
  ## **Deprecated since 0.9.6**: Use ``Uri`` instead.
  var urlS = $a
  var bS = $b
  if urlS == "": return b
  if urlS[urlS.len-1] != '/':
    urlS.add('/')
  if bS[0] == '/':
    urlS.add(bS.substr(1))
  else:
    urlS.add(bs)
  result = Url(urlS)

proc add*(url: var Url, a: Url) {.deprecated: "use Uri instead".} =
  ## Appends url to url.
  ##
  ## **Deprecated since 0.9.6**: Use ``Uri`` instead.
  url = url / a
{.pop.}

proc encodeUrl*(s: string, usePlus=true): string =
  ## Encodes a URL according to RFC3986.
  ##
  ## This means that characters in the set
  ## ``{'a'..'z', 'A'..'Z', '0'..'9', '-', '.', '_', '~'}`` are
  ## carried over to the result.
  ## All other characters are encoded as ``''%xx'`` where ``xx``
  ## denotes its hexadecimal value.
  ##
  ## As a special rule, when the value of ``usePlus`` is true,
  ## spaces are encoded as ``'+'`` instead of ``'%20'``.
  result = newStringOfCap(s.len + s.len shr 2) # assume 12% non-alnum-chars
  let fromSpace = if usePlus: "+" else: "%20"
  for c in s:
    case c
    # https://tools.ietf.org/html/rfc3986#section-2.3
    of 'a'..'z', 'A'..'Z', '0'..'9', '-', '.', '_', '~': add(result, c)
    of ' ': add(result, fromSpace)
    else:
      add(result, '%')
      add(result, toHex(ord(c), 2))

proc decodeUrl*(s: string, decodePlus=true): string =
  ## Decodes a URL according to RFC3986.
  ##
  ## This means that any ``'%xx'`` (where ``xx`` denotes a hexadecimal
  ## value) are converted to the character with ordinal number ``xx``,
  ## and every other character is carried over.
  ##
  ## As a special rule, when the value of ``decodePlus`` is true, ``'+'``
  ## characters are converted to a space.
  proc handleHexChar(c: char, x: var int) {.inline.} =
    case c
    of '0'..'9': x = (x shl 4) or (ord(c) - ord('0'))
    of 'a'..'f': x = (x shl 4) or (ord(c) - ord('a') + 10)
    of 'A'..'F': x = (x shl 4) or (ord(c) - ord('A') + 10)
    else: assert(false)

  result = newString(s.len)
  var i = 0
  var j = 0
  while i < s.len:
    case s[i]
    of '%':
      var x = 0
      handleHexChar(s[i+1], x)
      handleHexChar(s[i+2], x)
      inc(i, 2)
      result[j] = chr(x)
    of '+':
      if decodePlus:
        result[j] = ' '
      else:
        result[j] = s[i]
    else: result[j] = s[i]
    inc(i)
    inc(j)
  setLen(result, j)

proc parseAuthority(authority: string, result: var Uri) =
  var i = 0
  var inPort = false
  var inIPv6 = false
  while i < authority.len:
    case authority[i]
    of '@':
      swap result.password, result.port
      result.port.setLen(0)
      swap result.username, result.hostname
      result.hostname.setLen(0)
      inPort = false
    of ':':
      if inIPv6:
        result.hostname.add(authority[i])
      else:
        inPort = true
    of '[':
      inIPv6 = true
    of ']':
      inIPv6 = false
    else:
      if inPort:
        result.port.add(authority[i])
      else:
        result.hostname.add(authority[i])
    i.inc

proc parsePath(uri: string, i: var int, result: var Uri) =

  i.inc parseUntil(uri, result.path, {'?', '#'}, i)

  # The 'mailto' scheme's PATH actually contains the hostname/username
  if cmpIgnoreCase(result.scheme, "mailto") == 0:
    parseAuthority(result.path, result)
    result.path.setLen(0)

  if i < uri.len and uri[i] == '?':
    i.inc # Skip '?'
    i.inc parseUntil(uri, result.query, {'#'}, i)

  if i < uri.len and uri[i] == '#':
    i.inc # Skip '#'
    i.inc parseUntil(uri, result.anchor, {}, i)

proc initUri*(): Uri =
  ## Initializes a URI.
  result = Uri(scheme: "", username: "", password: "", hostname: "", port: "",
                path: "", query: "", anchor: "")

proc resetUri(uri: var Uri) =
  for f in uri.fields:
    when f is string:
      f.setLen(0)
    else:
      f = false

proc parseUri*(uri: string, result: var Uri) =
  ## Parses a URI. The `result` variable will be cleared before.
  resetUri(result)

  var i = 0

  # Check if this is a reference URI (relative URI)
  let doubleSlash = uri.len > 1 and uri[1] == '/'
  if i < uri.len and uri[i] == '/':
    # Make sure ``uri`` doesn't begin with '//'.
    if not doubleSlash:
      parsePath(uri, i, result)
      return

  # Scheme
  i.inc parseWhile(uri, result.scheme, Letters + Digits + {'+', '-', '.'}, i)
  if (i >= uri.len or uri[i] != ':') and not doubleSlash:
    # Assume this is a reference URI (relative URI)
    i = 0
    result.scheme.setLen(0)
    parsePath(uri, i, result)
    return
  if not doubleSlash:
    i.inc # Skip ':'

  # Authority
  if i+1 < uri.len and uri[i] == '/' and uri[i+1] == '/':
    i.inc(2) # Skip //
    var authority = ""
    i.inc parseUntil(uri, authority, {'/', '?', '#'}, i)
    if authority.len > 0:
      parseAuthority(authority, result)
  else:
    result.opaque = true

  # Path
  parsePath(uri, i, result)

proc parseUri*(uri: string): Uri =
  ## Parses a URI and returns it.
  result = initUri()
  parseUri(uri, result)

proc removeDotSegments(path: string): string =
  if path.len == 0: return ""
  var collection: seq[string] = @[]
  let endsWithSlash = path[path.len-1] == '/'
  var i = 0
  var currentSegment = ""
  while i < path.len:
    case path[i]
    of '/':
      collection.add(currentSegment)
      currentSegment = ""
    of '.':
      if i+2 < path.len and path[i+1] == '.' and path[i+2] == '/':
        if collection.len > 0:
          discard collection.pop()
          i.inc 3
          continue
      elif path[i+1] == '/':
        i.inc 2
        continue
      currentSegment.add path[i]
    else:
      currentSegment.add path[i]
    i.inc
  if currentSegment != "":
    collection.add currentSegment

  result = collection.join("/")
  if endsWithSlash: result.add '/'

proc merge(base, reference: Uri): string =
  # http://tools.ietf.org/html/rfc3986#section-5.2.3
  if base.hostname != "" and base.path == "":
    '/' & reference.path
  else:
    let lastSegment = rfind(base.path, "/")
    if lastSegment == -1:
      reference.path
    else:
      base.path[0 .. lastSegment] & reference.path

proc combine*(base: Uri, reference: Uri): Uri =
  ## Combines a base URI with a reference URI.
  ##
  ## This uses the algorithm specified in
  ## `section 5.2.2 of RFC 3986 <http://tools.ietf.org/html/rfc3986#section-5.2.2>`_.
  ##
  ## This means that the slashes inside the base URI's path as well as reference
  ## URI's path affect the resulting URI.
  ##
  ## For building URIs you may wish to use \`/\` instead.
  ##
  ## Examples:
  ##
  ## .. code-block::
  ##   let foo = combine(parseUri("http://example.com/foo/bar"), parseUri("/baz"))
  ##   assert foo.path == "/baz"
  ##
  ##   let bar = combine(parseUri("http://example.com/foo/bar"), parseUri("baz"))
  ##   assert bar.path == "/foo/baz"
  ##
  ##   let bar = combine(parseUri("http://example.com/foo/bar/"), parseUri("baz"))
  ##   assert bar.path == "/foo/bar/baz"

  template setAuthority(dest, src): untyped =
    dest.hostname = src.hostname
    dest.username = src.username
    dest.port = src.port
    dest.password = src.password

  result = initUri()
  if reference.scheme != base.scheme and reference.scheme != "":
    result = reference
    result.path = removeDotSegments(result.path)
  else:
    if reference.hostname != "":
      setAuthority(result, reference)
      result.path = removeDotSegments(reference.path)
      result.query = reference.query
    else:
      if reference.path == "":
        result.path = base.path
        if reference.query != "":
          result.query = reference.query
        else:
          result.query = base.query
      else:
        if reference.path.startsWith("/"):
          result.path = removeDotSegments(reference.path)
        else:
          result.path = removeDotSegments(merge(base, reference))
        result.query = reference.query
      setAuthority(result, base)
    result.scheme = base.scheme
  result.anchor = reference.anchor

proc combine*(uris: varargs[Uri]): Uri =
  ## Combines multiple URIs together.
  result = uris[0]
  for i in 1 ..< uris.len:
    result = combine(result, uris[i])

proc isAbsolute*(uri: Uri): bool =
  ## returns true if URI is absolute, false otherwise
  return uri.scheme != "" and (uri.hostname != "" or uri.path != "")

proc `/`*(x: Uri, path: string): Uri =
  ## Concatenates the path specified to the specified URI's path.
  ##
  ## Contrary to the ``combine`` procedure you do not have to worry about
  ## the slashes at the beginning and end of the path and URI's path
  ## respectively.
  ##
  ## Examples:
  ##
  ## .. code-block::
  ##   let foo = parseUri("http://example.com/foo/bar") / "/baz"
  ##   assert foo.path == "/foo/bar/baz"
  ##
  ##   let bar = parseUri("http://example.com/foo/bar") / "baz"
  ##   assert bar.path == "/foo/bar/baz"
  ##
  ##   let bar = parseUri("http://example.com/foo/bar/") / "baz"
  ##   assert bar.path == "/foo/bar/baz"
  result = x

  if result.path.len == 0:
    if path.len == 0 or path[0] != '/':
      result.path = "/"
    result.path.add(path)
    return

  if result.path.len > 0 and result.path[result.path.len-1] == '/':
    if path.len > 0 and path[0] == '/':
      result.path.add(path[1 .. path.len-1])
    else:
      result.path.add(path)
  else:
    if path.len == 0 or path[0] != '/':
      result.path.add '/'
    result.path.add(path)

proc `$`*(u: Uri): string =
  ## Returns the string representation of the specified URI object.
  result = ""
  if u.scheme.len > 0:
    result.add(u.scheme)
    if u.opaque:
      result.add(":")
    else:
      result.add("://")
  if u.username.len > 0:
    result.add(u.username)
    if u.password.len > 0:
      result.add(":")
      result.add(u.password)
    result.add("@")
  if u.hostname.endswith('/'):
    result.add(u.hostname[0..^2])
  else:
    result.add(u.hostname)
  if u.port.len > 0:
    result.add(":")
    result.add(u.port)
  if u.path.len > 0:
    if u.hostname.len > 0 and u.path[0] != '/':
      result.add('/')
    result.add(u.path)
  if u.query.len > 0:
    result.add("?")
    result.add(u.query)
  if u.anchor.len > 0:
    result.add("#")
    result.add(u.anchor)

when isMainModule:
  block:
    const test1 = "abc\L+def xyz"
    doAssert encodeUrl(test1) == "abc%0A%2Bdef+xyz"
    doAssert decodeUrl(encodeUrl(test1)) == test1
    doAssert encodeUrl(test1, false) == "abc%0A%2Bdef%20xyz"
    doAssert decodeUrl(encodeUrl(test1, false), false) == test1
    doAssert decodeUrl(encodeUrl(test1)) == test1

  block:
    let str = "http://localhost"
    let test = parseUri(str)
    doAssert test.path == ""

  block:
    let str = "http://localhost/"
    let test = parseUri(str)
    doAssert test.path == "/"

  block:
    let str = "http://localhost:8080/test"
    let test = parseUri(str)
    doAssert test.scheme == "http"
    doAssert test.port == "8080"
    doAssert test.path == "/test"
    doAssert test.hostname == "localhost"
    doAssert($test == str)

  block:
    let str = "foo://username:password@example.com:8042/over/there" &
              "/index.dtb?type=animal&name=narwhal#nose"
    let test = parseUri(str)
    doAssert test.scheme == "foo"
    doAssert test.username == "username"
    doAssert test.password == "password"
    doAssert test.hostname == "example.com"
    doAssert test.port == "8042"
    doAssert test.path == "/over/there/index.dtb"
    doAssert test.query == "type=animal&name=narwhal"
    doAssert test.anchor == "nose"
    doAssert($test == str)

  block:
    # IPv6 address
    let str = "foo://[::1]:1234/bar?baz=true&qux#quux"
    let uri = parseUri(str)
    doAssert uri.scheme == "foo"
    doAssert uri.hostname == "::1"
    doAssert uri.port == "1234"
    doAssert uri.path == "/bar"
    doAssert uri.query == "baz=true&qux"
    doAssert uri.anchor == "quux"

  block:
    let str = "urn:example:animal:ferret:nose"
    let test = parseUri(str)
    doAssert test.scheme == "urn"
    doAssert test.path == "example:animal:ferret:nose"
    doAssert($test == str)

  block:
    let str = "mailto:username@example.com?subject=Topic"
    let test = parseUri(str)
    doAssert test.scheme == "mailto"
    doAssert test.username == "username"
    doAssert test.hostname == "example.com"
    doAssert test.query == "subject=Topic"
    doAssert($test == str)

  block:
    let str = "magnet:?xt=urn:sha1:72hsga62ba515sbd62&dn=foobar"
    let test = parseUri(str)
    doAssert test.scheme == "magnet"
    doAssert test.query == "xt=urn:sha1:72hsga62ba515sbd62&dn=foobar"
    doAssert($test == str)

  block:
    let str = "/test/foo/bar?q=2#asdf"
    let test = parseUri(str)
    doAssert test.scheme == ""
    doAssert test.path == "/test/foo/bar"
    doAssert test.query == "q=2"
    doAssert test.anchor == "asdf"
    doAssert($test == str)

  block:
    let str = "test/no/slash"
    let test = parseUri(str)
    doAssert test.path == "test/no/slash"
    doAssert($test == str)

  block:
    let str = "//git@github.com:dom96/packages"
    let test = parseUri(str)
    doAssert test.scheme == ""
    doAssert test.username == "git"
    doAssert test.hostname == "github.com"
    doAssert test.port == "dom96"
    doAssert test.path == "/packages"

  block:
    let str = "file:///foo/bar/baz.txt"
    let test = parseUri(str)
    doAssert test.scheme == "file"
    doAssert test.username == ""
    doAssert test.hostname == ""
    doAssert test.port == ""
    doAssert test.path == "/foo/bar/baz.txt"

  # Remove dot segments tests
  block:
    doAssert removeDotSegments("/foo/bar/baz") == "/foo/bar/baz"

  # Combine tests
  block:
    let concat = combine(parseUri("http://google.com/foo/bar/"), parseUri("baz"))
    doAssert concat.path == "/foo/bar/baz"
    doAssert concat.hostname == "google.com"
    doAssert concat.scheme == "http"

  block:
    let concat = combine(parseUri("http://google.com/foo"), parseUri("/baz"))
    doAssert concat.path == "/baz"
    doAssert concat.hostname == "google.com"
    doAssert concat.scheme == "http"

  block:
    let concat = combine(parseUri("http://google.com/foo/test"), parseUri("bar"))
    doAssert concat.path == "/foo/bar"

  block:
    let concat = combine(parseUri("http://google.com/foo/test"), parseUri("/bar"))
    doAssert concat.path == "/bar"

  block:
    let concat = combine(parseUri("http://google.com/foo/test"), parseUri("bar"))
    doAssert concat.path == "/foo/bar"

  block:
    let concat = combine(parseUri("http://google.com/foo/test/"), parseUri("bar"))
    doAssert concat.path == "/foo/test/bar"

  block:
    let concat = combine(parseUri("http://google.com/foo/test/"), parseUri("bar/"))
    doAssert concat.path == "/foo/test/bar/"

  block:
    let concat = combine(parseUri("http://google.com/foo/test/"), parseUri("bar/"),
                         parseUri("baz"))
    doAssert concat.path == "/foo/test/bar/baz"

  # `/` tests
  block:
    let test = parseUri("http://example.com/foo") / "bar/asd"
    doAssert test.path == "/foo/bar/asd"

  block:
    let test = parseUri("http://example.com/foo/") / "/bar/asd"
    doAssert test.path == "/foo/bar/asd"

  # removeDotSegments tests
  block:
    # empty test
    doAssert removeDotSegments("") == ""

  # bug #3207
  block:
    doAssert parseUri("http://qq/1").combine(parseUri("https://qqq")).`$` == "https://qqq"

  # bug #4959
  block:
    let foo = parseUri("http://example.com") / "/baz"
    doAssert foo.path == "/baz"

  # bug found on stream 13/10/17
  block:
    let foo = parseUri("http://localhost:9515") / "status"
    doAssert $foo == "http://localhost:9515/status"

  # bug #6649 #6652
  block:
    var foo = parseUri("http://example.com")
    foo.hostname = "example.com"
    foo.path = "baz"
    doAssert $foo == "http://example.com/baz"

    foo.hostname = "example.com/"
    foo.path = "baz"
    doAssert $foo == "http://example.com/baz"

    foo.hostname = "example.com"
    foo.path = "/baz"
    doAssert $foo == "http://example.com/baz"

    foo.hostname = "example.com/"
    foo.path = "/baz"
    doAssert $foo == "http://example.com/baz"

    foo.hostname = "example.com/"
    foo.port = "8000"
    foo.path = "baz"
    doAssert $foo == "http://example.com:8000/baz"

    foo = parseUri("file:/dir/file")
    foo.path = "relative"
    doAssert $foo == "file:relative"

  # isAbsolute tests
  block:
    doAssert "www.google.com".parseUri().isAbsolute() == false
    doAssert "http://www.google.com".parseUri().isAbsolute() == true
    doAssert "file:/dir/file".parseUri().isAbsolute() == true
    doAssert "file://localhost/dir/file".parseUri().isAbsolute() == true
    doAssert "urn:ISSN:1535-3613".parseUri().isAbsolute() == true

    # path-relative URL *relative
    doAssert "about".parseUri().isAbsolute == false
    doAssert "about/staff.html".parseUri().isAbsolute == false
    doAssert "about/staff.html?".parseUri().isAbsolute == false
    doAssert "about/staff.html?parameters".parseUri().isAbsolute == false

    # absolute-path-relative URL *relative
    doAssert "/".parseUri().isAbsolute == false
    doAssert "/about".parseUri().isAbsolute == false
    doAssert "/about/staff.html".parseUri().isAbsolute == false
    doAssert "/about/staff.html?".parseUri().isAbsolute == false
    doAssert "/about/staff.html?parameters".parseUri().isAbsolute == false

    # scheme-relative URL *relative
    doAssert "//username:password@example.com:8888".parseUri().isAbsolute == false
    doAssert "//username@example.com".parseUri().isAbsolute == false
    doAssert "//example.com".parseUri().isAbsolute == false
    doAssert "//example.com/".parseUri().isAbsolute == false
    doAssert "//example.com/about".parseUri().isAbsolute == false
    doAssert "//example.com/about/staff.html".parseUri().isAbsolute == false
    doAssert "//example.com/about/staff.html?".parseUri().isAbsolute == false
    doAssert "//example.com/about/staff.html?parameters".parseUri().isAbsolute == false

    # absolute URL *absolute
    doAssert "https://username:password@example.com:8888".parseUri().isAbsolute == true
    doAssert "https://username@example.com".parseUri().isAbsolute == true
    doAssert "https://example.com".parseUri().isAbsolute == true
    doAssert "https://example.com/".parseUri().isAbsolute == true
    doAssert "https://example.com/about".parseUri().isAbsolute == true
    doAssert "https://example.com/about/staff.html".parseUri().isAbsolute == true
    doAssert "https://example.com/about/staff.html?".parseUri().isAbsolute == true
    doAssert "https://example.com/about/staff.html?parameters".parseUri().isAbsolute == true

  echo("All good!")