// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
use crate::swc_common;
use crate::swc_common::comments::Comments;
use crate::swc_common::errors::Diagnostic;
use crate::swc_common::errors::DiagnosticBuilder;
use crate::swc_common::errors::Emitter;
use crate::swc_common::errors::Handler;
use crate::swc_common::errors::HandlerFlags;
use crate::swc_common::FileName;
use crate::swc_common::Globals;
use crate::swc_common::SourceMap;
use crate::swc_common::Span;
use crate::swc_ecma_ast;
use crate::swc_ecma_parser::lexer::Lexer;
use crate::swc_ecma_parser::JscTarget;
use crate::swc_ecma_parser::Parser;
use crate::swc_ecma_parser::Session;
use crate::swc_ecma_parser::SourceFileInput;
use crate::swc_ecma_parser::Syntax;
use crate::swc_ecma_parser::TsConfig;

use std::error::Error;
use std::fmt;
use std::sync::Arc;
use std::sync::RwLock;

#[derive(Clone, Debug)]
pub struct SwcDiagnosticBuffer {
  pub diagnostics: Vec<Diagnostic>,
}

impl Error for SwcDiagnosticBuffer {}

impl fmt::Display for SwcDiagnosticBuffer {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    let msg = self
      .diagnostics
      .iter()
      .map(|d| d.message())
      .collect::<Vec<String>>()
      .join(",");

    f.pad(&msg)
  }
}

#[derive(Clone)]
pub struct SwcErrorBuffer(Arc<RwLock<SwcDiagnosticBuffer>>);

impl SwcErrorBuffer {
  pub fn default() -> Self {
    Self(Arc::new(RwLock::new(SwcDiagnosticBuffer {
      diagnostics: vec![],
    })))
  }
}

impl Emitter for SwcErrorBuffer {
  fn emit(&mut self, db: &DiagnosticBuilder) {
    self.0.write().unwrap().diagnostics.push((**db).clone());
  }
}

impl From<SwcErrorBuffer> for SwcDiagnosticBuffer {
  fn from(buf: SwcErrorBuffer) -> Self {
    let s = buf.0.read().unwrap();
    s.clone()
  }
}

/// Low-level utility structure with common AST parsing functions.
///
/// Allows to build more complicated parser by providing a callback
/// to `parse_module`.
pub struct AstParser {
  pub buffered_error: SwcErrorBuffer,
  pub source_map: Arc<SourceMap>,
  pub handler: Handler,
  pub comments: Comments,
  pub globals: Globals,
}

impl AstParser {
  pub fn new() -> Self {
    let buffered_error = SwcErrorBuffer::default();

    let handler = Handler::with_emitter_and_flags(
      Box::new(buffered_error.clone()),
      HandlerFlags {
        dont_buffer_diagnostics: true,
        can_emit_warnings: true,
        ..Default::default()
      },
    );

    AstParser {
      buffered_error,
      source_map: Arc::new(SourceMap::default()),
      handler,
      comments: Comments::default(),
      globals: Globals::new(),
    }
  }

  pub fn parse_module<F, R>(
    &self,
    file_name: &str,
    source_code: &str,
    callback: F,
  ) -> R
  where
    F: FnOnce(Result<swc_ecma_ast::Module, SwcDiagnosticBuffer>) -> R,
  {
    swc_common::GLOBALS.set(&self.globals, || {
      let swc_source_file = self.source_map.new_source_file(
        FileName::Custom(file_name.to_string()),
        source_code.to_string(),
      );

      let buffered_err = self.buffered_error.clone();
      let session = Session {
        handler: &self.handler,
      };

      let mut ts_config = TsConfig::default();
      ts_config.dynamic_import = true;
      let syntax = Syntax::Typescript(ts_config);

      let lexer = Lexer::new(
        session,
        syntax,
        JscTarget::Es2019,
        SourceFileInput::from(&*swc_source_file),
        Some(&self.comments),
      );

      let mut parser = Parser::new_from(session, lexer);

      let parse_result =
        parser
          .parse_module()
          .map_err(move |mut err: DiagnosticBuilder| {
            err.cancel();
            SwcDiagnosticBuffer::from(buffered_err)
          });

      callback(parse_result)
    })
  }

  pub fn get_span_location(&self, span: Span) -> swc_common::Loc {
    self.source_map.lookup_char_pos(span.lo())
  }

  pub fn get_span_comments(
    &self,
    span: Span,
  ) -> Vec<swc_common::comments::Comment> {
    self
      .comments
      .take_leading_comments(span.lo())
      .unwrap_or_else(|| vec![])
  }
}