/**
 * Copyright (C) 2009-2011 the original author or authors.
 * See the notice.md file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * 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.
 */
package org.fusesource.scalate.scaml

import org.fusesource.scalate._
import org.fusesource.scalate.support.{ AbstractCodeGenerator, Code, RenderHelper, Text }

import scala.collection.mutable.LinkedHashMap
import scala.language.implicitConversions
import scala.util.parsing.input.OffsetPosition

/**
 * Generates a scala class given a HAML document
 *
 * @author <a href="http://hiramchirino.com">Hiram Chirino</a>
 */
class ScamlCodeGenerator extends AbstractCodeGenerator[Statement] {
  override val stratumName = "SCAML"

  implicit def textToString(text: Text) = text.value

  implicit def textOptionToString(text: Option[Text]): Option[String] = text match {
    case None => None
    case Some(x) => Some(x.value)
  }

  protected class SourceBuilder extends AbstractSourceBuilder[Statement] {
    val text_buffer = new StringBuffer
    var element_level = 0
    var pending_newline = false
    var suppress_indent = false
    var in_html_comment = false

    override def current_position = {
      if (text_buffer.length == 0) {
        super.current_position
      } else {
        super.current_position + ("$_scalate_$_context << ( " + asString(text_buffer.toString)).length
      }
    }

    def write_indent() = {
      if (pending_newline) {
        text_buffer.append(ScamlOptions.nl)
        pending_newline = false
      }
      if (suppress_indent) {
        suppress_indent = false
      } else {
        text_buffer.append(indent_string)
      }
    }

    def indent_string() = {
      val rc = new StringBuilder
      for (i <- 0 until element_level) {
        rc.append(ScamlOptions.indent)
      }
      rc.toString
    }

    def trim_whitespace() = {
      pending_newline = false
      suppress_indent = true
    }

    def write_text(value: String) = {
      text_buffer.append(value)
    }

    def write_nl() = {
      pending_newline = true
    }

    def flush_text() = {
      if (pending_newline) {
        text_buffer.append(ScamlOptions.nl)
        pending_newline = false
      }
      if (text_buffer.length > 0) {
        this << "$_scalate_$_context << ( " + asString(text_buffer.toString) + " );"
        text_buffer.setLength(0)
      }
    }

    override def generateInitialImports = {
      this << "import _root_.org.fusesource.scalate.support.RenderHelper.{sanitize=>$_scalate_$_sanitize, preserve=>$_scalate_$_preserve, indent=>$_scalate_$_indent, smart_sanitize=>$_scalate_$_smart_sanitize, attributes=>$_scalate_$_attributes}"
    }

    def generate(statements: List[Statement]): Unit = {
      generate_with_flush(statements)
    }

    def generate_with_flush(statements: List[Statement]): Unit = {
      generate_no_flush(statements)
      flush_text
    }

    def generate_no_flush(statements: List[Statement]): Unit = {

      var remaining = statements
      while (remaining != Nil) {
        val fragment = remaining.head
        remaining = remaining.drop(1)

        fragment match {
          case attribute: Attribute =>
            this << attribute.pos
            generateBindings(List(Binding(attribute.name.value, attribute.className.value, attribute.autoImport, attribute.defaultValue,
              classNamePositional = Some(attribute.className), defaultValuePositional = attribute.defaultValue))) {
              generate(remaining)
            }
            remaining = Nil

          case _ =>
            generate(fragment)
        }
      }

    }

    def generate(statement: Statement): Unit = {
      statement match {
        case s: Newline => {
        }
        case s: Attribute => {
        }
        case s: ScamlComment => {
          generate(s)
        }
        case s: TextExpression => {
          generateTextExpression(s, true)
        }
        case s: HtmlComment => {
          generate(s)
        }
        case s: Element => {
          generate(s)
        }
        case s: Executed => {
          generate(s)
        }
        case s: FilterStatement => {
          generate(s)
        }
        case s: Doctype => {
          generate(s)
        }
      }
    }

    def generate(statement: Doctype): Unit = {
      this << statement.pos
      write_indent
      statement.line.map { _.value } match {
        case List("XML") =>
          write_text("<?xml version=\"1.0\" encoding=\"utf-8\" ?>")
        case List("XML", encoding) =>
          write_text("<?xml version=\"1.0\" encoding=\"" + encoding + "\" ?>")
        case _ =>
          ScamlOptions.format match {
            case ScamlOptions.Format.xhtml =>
              statement.line.map { _.value } match {
                case List("Strict") =>
                  write_text("""<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">""")
                case List("Frameset") =>
                  write_text("""<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">""")
                case List("5") =>
                  write_text("""<!DOCTYPE html>""")
                case List("1.1") =>
                  write_text("""<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">""")
                case List("Basic") =>
                  write_text("""<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN" "http://www.w3.org/TR/xhtml-basic/xhtml-basic11.dtd"> """)
                case List("Mobile") =>
                  write_text("""<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.2//EN" "http://www.openmobilealliance.org/tech/DTD/xhtml-mobile12.dtd">""")
                case _ =>
                  write_text("""<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">""")
              }
            case ScamlOptions.Format.html4 =>
              statement.line.map { _.value } match {
                case List("Strict") =>
                  write_text("""<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">""")
                case List("Frameset") =>
                  write_text("""<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">""")
                case _ =>
                  write_text("""<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">""")
              }
            case ScamlOptions.Format.html5 =>
              write_text("""<!DOCTYPE html>""")

          }
      }
      write_nl
    }

    def generate(statement: FilterStatement): Unit = {

      def isEnabled(flag: String) = {
        statement.flags.contains(Text(flag))
      }
      if (isEnabled("&") && isEnabled("!")) {
        throw new InvalidSyntaxException("Cannot use both the '&' and '!' filter flags together.", statement.pos)
      }

      val preserve = isEnabled("~")
      val interpolate = isEnabled("&") || isEnabled("!")
      val sanitize = interpolate && isEnabled("&")

      val content = statement.body.map { _.value }.mkString(ScamlOptions.nl)

      val text: TextExpression = if (interpolate) {
        val p = new ScamlParser(ScamlParser.UPTO_TYPE_MULTI_LINE)
        try {
          p.parse(p.literal_text(Some(sanitize)), content)
        } catch {
          case e: InvalidSyntaxException =>
            val pos = statement.body.head.pos.asInstanceOf[OffsetPosition]
            throw new InvalidSyntaxException(e.brief, OffsetPosition(pos.source, pos.offset + e.pos.column))
        }
      } else {
        LiteralText(List(Text(content)), Some(sanitize))
      }

      var prefix = "$_scalate_$_context << ( "
      var suffix = ");"

      if (ScamlOptions.ugly) {
        suppress_indent = true
      } else if (preserve) {
        prefix += " $_scalate_$_preserve ("
        suffix = ") " + suffix
      } else {
        prefix += "$_scalate_$_indent ( " + asString(indent_string()) + ", "
        suffix = ") " + suffix
      }

      for (f <- statement.filters) {
        prefix += "$_scalate_$_context.value ( _root_.org.fusesource.scalate.filter.FilterRequest(" + asString(f) + ", "
        suffix = ") ) " + suffix
      }

      write_indent
      flush_text

      this << prefix + "$_scalate_$_context.capture { "
      indent {
        generateTextExpression(text, false)
        flush_text
      }
      this << "} " + suffix
      write_nl
    }

    def generateTextExpression(statement: TextExpression, is_line: Boolean): Unit = {
      statement match {
        case s: LiteralText => {
          if (is_line) {
            write_indent
          }
          var literal = true
          for (part <- s.text) {
            // alternate between rendering literal and interpolated text
            if (literal) {
              write_text(part)
              literal = false
            } else {
              flush_text
              s.sanitize match {
                case None =>
                  this << "$_scalate_$_context <<< ( " :: part :: " );" :: Nil
                case Some(true) =>
                  this << "$_scalate_$_context.escape( " :: part :: " );" :: Nil
                case Some(false) =>
                  this << "$_scalate_$_context.unescape( " :: part :: " );" :: Nil
              }
              literal = true
            }
          }
          if (is_line) {
            write_nl
          }
        }
        case s: EvaluatedText => {

          var prefix = "$_scalate_$_context << ("
          var suffix = ");"

          if (s.preserve || ScamlOptions.ugly) {
            if (s.ugly || ScamlOptions.ugly) {
              suppress_indent = true
            } else {
              prefix += " $_scalate_$_preserve ("
              suffix = ") " + suffix
            }
          } else {
            prefix += " $_scalate_$_indent ( " + asString(indent_string()) + ","
            suffix = ") " + suffix
          }

          val method = s.sanitize match {
            case Some(true) =>
              "valueEscaped"
            case Some(false) =>
              "valueUnescaped"
            case _ =>
              "value"
          }
          prefix += " $_scalate_$_context." + method + "("
          suffix = ") " + suffix

          if (is_line) {
            write_indent
          }
          flush_text
          if (s.body.isEmpty) {
            this << prefix
            indent {
              this << s.code
            }
            this << suffix
          } else {
            this << prefix
            indent {
              this << s.code :: " {" :: Nil
              indent {
                generate_with_flush(s.body)
              }
              this << "}"
            }
            this << suffix
          }
          if (is_line) {
            write_nl
          }
        }
      }
    }

    def generate(statement: Executed): Unit = {
      flush_text
      if (statement.body.isEmpty) {
        statement.code.foreach {
          (line) =>
            this << line :: Nil
        }
      } else {
        statement.code.foreach {
          (line) =>
            if (line ne statement.code.last) {
              this << line :: Nil
            } else {
              this << line :: "{" :: Nil
            }
        }
        indent {
          generate_no_flush(statement.body)
          flush_text
        }
        this << "}"
      }
    }

    def generate(statement: HtmlComment): Unit = {
      //  case class HtmlComment(conditional:Option[String], text:Option[String], body:List[Statement]) extends Statement
      var prefix = "<!--"
      var suffix = "-->"
      if (statement.conditional.isDefined) {
        prefix = "<!--[" + statement.conditional.get + "]>"
        suffix = "<![endif]-->"
      }

      // To support comment within comment blocks.
      if (in_html_comment) {
        prefix = ""
        suffix = ""
      } else {
        in_html_comment = true
      }

      statement match {
        case HtmlComment(_, text, List()) => {
          write_indent
          this << statement.pos
          write_text(prefix + " ")
          if (text.isDefined) {
            this << text.get.pos
            write_text(text.get.trim)
          }
          write_text(" " + suffix)
          write_nl
        }
        case HtmlComment(_, None, list) => {
          write_indent
          this << statement.pos
          write_text(prefix)
          write_nl

          element_level += 1
          generate_no_flush(list)
          element_level -= 1

          write_indent
          write_text(suffix)
          write_nl
        }
        case _ => throw new InvalidSyntaxException("Illegal nesting: content can't be both given on the same line as html comment and nested within it", statement.pos);
      }

      if (prefix.length != 0) {
        in_html_comment = false
      }
    }

    def generate(statement: ScamlComment): Unit = {
      this << statement.pos
      statement match {
        case ScamlComment(text, List()) => {
          this << "//" :: text.getOrElse("") :: Nil
        }
        case ScamlComment(text, list) => {
          this << "/*" :: text.getOrElse("") :: Nil
          list.foreach(x => {
            this << " * " :: x :: Nil
          })
          this << " */"
        }
      }
    }

    def isAutoClosed(statement: Element) = {
      statement.text == None && statement.body.isEmpty &&
        statement.tag.isDefined && (ScamlOptions.autoclose == null || ScamlOptions.autoclose.contains(statement.tag.get.value))
    }

    def generate(statement: Element): Unit = {

      val tag = statement.tag.getOrElse("div")
      if (statement.text.isDefined && !statement.body.isEmpty) {
        throw new InvalidSyntaxException("Illegal nesting: content can't be given on the same line as html element or nested within it if the tag is closed", statement.pos)
      }

      def write_start_tag = {
        write_text("<" + tag)
        write_attributes(statement.attributes)
        if (statement.close || isAutoClosed(statement)) {
          write_text("/>")
        } else {
          write_text(">")
        }
      }

      def write_end_tag = {
        if (statement.close || isAutoClosed(statement)) {
          write_text("")
        } else {
          write_text("</" + tag + ">")
        }
      }

      statement.trim match {
        case Some(Trim.Outer) => {
        }
        case Some(Trim.Inner) => {}
        case Some(Trim.Both) => {}
        case _ => {}
      }

      def outer_trim = statement.trim match {
        case Some(Trim.Outer) => { trim_whitespace; true }
        case Some(Trim.Both) => { trim_whitespace; true }
        case _ => { false }
      }

      def inner_trim = statement.trim match {
        case Some(Trim.Inner) => { trim_whitespace; true }
        case Some(Trim.Both) => { trim_whitespace; true }
        case _ => { false }
      }

      outer_trim
      this << statement.pos
      write_indent
      write_start_tag

      statement match {
        case Element(_, _, text, List(), _, _) => {
          generateTextExpression(text.getOrElse(LiteralText(List(Text("")), Some(false))), false)
          write_end_tag
          write_nl
          outer_trim
        }
        case Element(_, _, None, list, _, _) => {
          write_nl

          if (!inner_trim) {
            element_level += 1
          }
          generate_no_flush(list)
          if (!inner_trim) {
            element_level -= 1
          }

          write_indent
          write_end_tag
          write_nl
          outer_trim
        }
        case _ => throw new InvalidSyntaxException("Illegal nesting: content can't be both given on the same line as html element and nested within it", statement.pos);
      }
    }

    def write_attributes(entries: List[(Any, Any)]) = {

      // Check to see if it's a dynamic attribute list
      var dynamic = false

      def check(n: Any): Unit = n match {
        case x: EvaluatedText =>
          dynamic = true
        case x: LiteralText =>
          if (x.text.length > 1) {
            dynamic = true
          }
        case _ =>
      }

      for ((k, v) <- entries) {
        check(k)
        check(v)
      }
      if (dynamic) {

        def write_expression(expression: Any) = {
          expression match {
            case s: String =>
              this << asString(s)
            case s: Text =>
              this << s.pos
              this << asString(s)
            case s: LiteralText =>
              this << s.pos
              var literal = true
              val parts = s.text.map { part =>
                // alternate between rendering literal and interpolated expression
                if (literal) {
                  literal = !literal
                  asString(part) :: Nil
                } else {
                  literal = !literal
                  List[AnyRef]("$_scalate_$_context.value(", part, ", false)")
                }
              }
              this << parts.foldRight(List[AnyRef]()) {
                case (prev, sum) =>
                  sum match {
                    case List() => prev
                    case _ => prev ::: " + " :: sum
                  }
              }
              flush_text
            case s: EvaluatedText =>
              if (s.body.isEmpty) {
                this << s.code :: Nil
              } else {
                this << s.code :: " {" :: Nil
                indent {
                  generate_with_flush(s.body)
                }
                this << "} "
              }
            case _ => throw new UnsupportedOperationException("don't know how to eval: " + expression);
          }
        }

        flush_text
        this << "$_scalate_$_context << $_scalate_$_attributes( $_scalate_$_context, List( ("
        indent {
          var first = true
          entries.foreach {
            (entry) =>
              if (!first) {
                this << "), ("
              }
              first = false
              indent {
                write_expression(entry._1)
              }
              this << ","
              indent {
                write_expression(entry._2)
              }
          }
        }
        this << ") ) )"

      } else {

        def value_of(value: Any): Text = {
          value match {
            case LiteralText(text, _) => text.head
            case s: Text => s
            case _ => throw new UnsupportedOperationException("don't know how to deal with: " + value);
          }
        }

        val (entries_class, tmp) = entries.partition { x => { x._1 match { case "class" => true; case _ => false } } }
        val (entries_id, entries_rest) = tmp.partition { x => { x._1 match { case "id" => true; case _ => false } } }
        val map = LinkedHashMap[Text, Text]()

        if (!entries_id.isEmpty) {
          map += Text("id") -> value_of(entries_id.last._2)
        }

        if (!entries_class.isEmpty) {
          var value: Option[Text] = None
          value = entries_class.foldLeft(value) {
            (rc, x) =>
              rc match {
                case None => Some(value_of(x._2))
                case Some(y) => Some(y + " " + value_of(x._2))
              }
          }
          map += Text("class") -> value.get
        }

        entries_rest.foreach { me => map += value_of(me._1) -> value_of(me._2) }

        if (!map.isEmpty) {
          map.foreach {
            case (name, value) =>
              write_text(" ")
              this << name.pos
              write_text(name)
              write_text("=\"")
              this << value.pos
              write_text(RenderHelper.sanitize(value))
              write_text("\"")
          }
        }

      }
    }

  }

  override def generate(engine: TemplateEngine, source: TemplateSource, bindings: Iterable[Binding]): Code = {

    val uri = source.uri
    val hamlSource = source.text
    val statements = (new ScamlParser).parse(hamlSource)

    val builder = new SourceBuilder()
    builder.generate(engine, source, bindings, statements)
    Code(source.className, builder.code, Set(uri), builder.positions)
  }

}