/* -----------------------------------------------------------------------------
Copyright 2023-2024 Kevin P. Barry

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
----------------------------------------------------------------------------- */

// Author: Kevin P. Barry [ta0kira@gmail.com]

define TextStream {
  $ReadOnly[source]$

  @value String source
  @value Int tokenStart
  @value Int tokenEnd
  @value Int currentLine
  @value Int currentChar

  new (source) {
    return TextStream{ source, 0, 0, 1, 1 }
  }

  current () (char) {
    char <- empty
    if (tokenEnd < source.size()) {
      char <- source.readAt(tokenEnd)
    }
  }

  tokenSize () {
    return tokenEnd-tokenStart
  }

  forward () {
    if (tokenEnd < source.size()) {
      tokenEnd <- tokenEnd+1
    }
    return self
  }

  reset () {
    tokenEnd <- tokenStart
    return self
  }

  take () {
    cleanup {
      while (tokenStart < tokenEnd) {
        if (source.readAt(tokenStart) == '\n') {
          currentChar <- 1
          currentLine <- currentLine+1
        } else {
          currentChar <- currentChar+1
        }
      } update {
        tokenStart <- tokenStart+1
      }
      tokenStart <- tokenEnd
    } in return preview()
  }

  preview () {
    return source.subSequence(tokenStart, tokenSize())
  }

  currentLine () {
    return currentLine
  }

  currentChar () {
    return currentChar
  }

  atEnd () {
    return tokenStart >= source.size()
  }
}

define UnformattedFormatter {
  new () {
    return delegate -> #self
  }

  formatLeaf (_, value) {
    return value.formatted()
  }

  createSection (_) {
    return String.builder()
  }
}

define StreamTokenizer {
  $ReadOnlyExcept[]$

  @value #c context
  @value Tokenizer<#c, #v> tokenizer

  new (context, tokenizer) {
    return delegate -> StreamTokenizer<#c, #v>
  }

  tokenizeAll (input, output) {
    scoped {
      optional #v token <- empty
    } in while (!input.atEnd()) {
      token <- input `tokenizer.tokenize` context
    } update {
      // Process new token.
      if (`present` token) {
        \ output.append(`require` token)
      } else {
        // Tokenizing failed => let the caller deal with the rest of the input.
        break
      }
    }
    return self
  }
}

define CharType {
  $ReadOnlyExcept[]$

  @category KVReader<Char, String> escapes <- HashedMap<Char, String>.new()
      .set('\t', "\\t")
      .set('\n', "\\n")
      .set('\r', "\\r")
      .set('\"', "\\\"")
      .set('\\', "\\\\")

  @category SetReader<Char> binChars <- HashedSet<Char>.new() `AppendH:from` "01".defaultOrder()

  @category SetReader<Char> octChars <- HashedSet<Char>.new() `AppendH:from` "01234567".defaultOrder()

  @category SetReader<Char> decChars <- HashedSet<Char>.new() `AppendH:from` "0123456789".defaultOrder()

  @category SetReader<Char> hexChars <- HashedSet<Char>.new() `AppendH:from` "0123456789abcdefABCDEF".defaultOrder()

  @category SetReader<Char> whitespaceChars <- HashedSet<Char>.new() `AppendH:from` "\n\t\r ".defaultOrder()

  lower (c) {
    return c >= 'a' && c <= 'z'
  }

  upper (c) {
    return c >= 'A' && c <= 'Z'
  }

  digit (c) {
    return `decChars.member` c
  }

  binDigit (c) {
    return `binChars.member` c
  }

  octDigit (c) {
    return `octChars.member` c
  }

  hexDigit (c) {
    return `hexChars.member` c
  }

  alphaNum (c) {
    return lower(c) || upper(c) || digit(c)
  }

  whitespace (c) {
    return `whitespaceChars.member` c
  }

  binChars () {
    return binChars
  }

  octChars () {
    return octChars
  }

  decChars () {
    return decChars
  }

  hexChars () {
    return hexChars
  }

  oneOf (c, allowed) (match) {
    match <- false
    traverse (allowed.defaultOrder() -> Char c2) {
      if (c == c2) {
        return true
      }
    }
  }

  escapeBreaks (string) {
    [Append<Formatted> & Build<String>] builder <- String.builder()
    traverse (string.defaultOrder() -> Char c) {
      scoped {
        optional String replacement <- escapes.get(c)
      } in if (`present` replacement) {
        \ builder.append(`require` replacement)
      } else {
        \ builder.append(c)
      }
    }
    return builder.build()
  }
}