import Exception from '../exception';

export function SourceLocation(source, locInfo) {
  this.source = source;
  this.start = {
    line: locInfo.first_line,
    column: locInfo.first_column
  };
  this.end = {
    line: locInfo.last_line,
    column: locInfo.last_column
  };
}

export function id(token) {
  if (/^\[.*\]$/.test(token)) {
    return token.substr(1, token.length - 2);
  } else {
    return token;
  }
}

export function stripFlags(open, close) {
  return {
    open: open.charAt(2) === '~',
    close: close.charAt(close.length - 3) === '~'
  };
}

export function stripComment(comment) {
  return comment.replace(/^\{\{~?\!-?-?/, '')
                .replace(/-?-?~?\}\}$/, '');
}

export function preparePath(data, parts, locInfo) {
  locInfo = this.locInfo(locInfo);

  let original = data ? '@' : '',
      dig = [],
      depth = 0,
      depthString = '';

  for (let i = 0, l = parts.length; i < l; i++) {
    let part = parts[i].part,
        // If we have [] syntax then we do not treat path references as operators,
        // i.e. foo.[this] resolves to approximately context.foo['this']
        isLiteral = parts[i].original !== part;
    original += (parts[i].separator || '') + part;

    if (!isLiteral && (part === '..' || part === '.' || part === 'this')) {
      if (dig.length > 0) {
        throw new Exception('Invalid path: ' + original, {loc: locInfo});
      } else if (part === '..') {
        depth++;
        depthString += '../';
      }
    } else {
      dig.push(part);
    }
  }

  return new this.PathExpression(data, depth, dig, original, locInfo);
}

export function prepareMustache(path, params, hash, open, strip, locInfo) {
  // Must use charAt to support IE pre-10
  let escapeFlag = open.charAt(3) || open.charAt(2),
      escaped = escapeFlag !== '{' && escapeFlag !== '&';

  return new this.MustacheStatement(path, params, hash, escaped, strip, this.locInfo(locInfo));
}

export function prepareRawBlock(openRawBlock, contents, close, locInfo) {
  if (openRawBlock.path.original !== close) {
    let errorNode = {loc: openRawBlock.path.loc};

    throw new Exception(openRawBlock.path.original + " doesn't match " + close, errorNode);
  }

  locInfo = this.locInfo(locInfo);
  let program = new this.Program(contents, null, {}, locInfo);

  return new this.BlockStatement(
      openRawBlock.path, openRawBlock.params, openRawBlock.hash,
      program, undefined,
      {}, {}, {},
      locInfo);
}

export function prepareBlock(openBlock, program, inverseAndProgram, close, inverted, locInfo) {
  // When we are chaining inverse calls, we will not have a close path
  if (close && close.path && openBlock.path.original !== close.path.original) {
    let errorNode = {loc: openBlock.path.loc};

    throw new Exception(openBlock.path.original + ' doesn\'t match ' + close.path.original, errorNode);
  }

  program.blockParams = openBlock.blockParams;

  let inverse,
      inverseStrip;

  if (inverseAndProgram) {
    if (inverseAndProgram.chain) {
      inverseAndProgram.program.body[0].closeStrip = close.strip;
    }

    inverseStrip = inverseAndProgram.strip;
    inverse = inverseAndProgram.program;
  }

  if (inverted) {
    inverted = inverse;
    inverse = program;
    program = inverted;
  }

  return new this.BlockStatement(
      openBlock.path, openBlock.params, openBlock.hash,
      program, inverse,
      openBlock.strip, inverseStrip, close && close.strip,
      this.locInfo(locInfo));
}

export function prepareProgram(statements, loc) {
  if (!loc && statements.length) {
    const firstLoc = statements[0].loc,
          lastLoc = statements[statements.length - 1].loc;

    /* istanbul ignore else */
    if (firstLoc && lastLoc) {
      loc = {
        source: firstLoc.source,
        start: {
          line: firstLoc.start.line,
          column: firstLoc.start.column
        },
        end: {
          line: lastLoc.end.line,
          column: lastLoc.end.column
        }
      };
    }
  }

  return new this.Program(statements, null, {}, loc);
}