module.exports = class Compiler {
  constructor(tree, context) {
    this.tree = tree
    this.context = context
    this.result = ''
  }

  compile() {
    this.tree.forEach(node => {
      if (node.type === 'functionCall') {
        const attributes = node.args.map(
          arg =>
            `${arg.attributeName}="${this.compileAttribute(
              arg.attributeValue,
            )}"`,
        )
        const compiler = new Compiler(node.subtree, this.context)
        const content = compiler.compile()

        if (node.functionName) {
          this.result += `<${node.functionName}${
            attributes.length ? ' ' : ''
          }${attributes.join(' ')}>${content}</${node.functionName}>`
        } else {
          this.result += content
        }
      } else if (node.type === 'string') {
        this.result += node.content
      } else if (node.type === 'identifier') {
        this.result += this.lookup(node.name)
      } else if (node.type === 'each') {
        const symbol = node.symbol.value
        const subject = this.lookup(node.subject.name)
        subject.forEach(item => {
          let context = {}
          context[symbol] = item
          const compiler = new Compiler([node.body], context)
          this.result += compiler.compile()
        })
      }
    })

    return this.result.trim()
  }

  compileAttribute(attribute) {
    if (attribute.type === 'string') {
      return attribute.content
    } else if (attribute.type === 'identifier') {
      return this.lookup(attribute.name)
    }
  }

  lookup(name) {
    return this.context[name]
  }
}