/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

const { Cu } = require("chrome");
const {
  setBreakpointAtEntryPoints,
} = require("devtools/server/actors/breakpoint");
const { ActorClassWithSpec, Actor } = require("devtools/shared/protocol");
const DevToolsUtils = require("devtools/shared/DevToolsUtils");
const { assert } = DevToolsUtils;
const { sourceSpec } = require("devtools/shared/specs/source");
const {
  resolveSourceURL,
  getSourcemapBaseURL,
} = require("devtools/server/actors/utils/source-map-utils");

loader.lazyRequireGetter(
  this,
  "ArrayBufferActor",
  "devtools/server/actors/array-buffer",
  true
);
loader.lazyRequireGetter(
  this,
  "LongStringActor",
  "devtools/server/actors/string",
  true
);

loader.lazyRequireGetter(this, "Services");
loader.lazyGetter(
  this,
  "WebExtensionPolicy",
  () => Cu.getGlobalForObject(Cu).WebExtensionPolicy
);

function isEvalSource(source) {
  const introType = source.introductionType;

  // Script elements that are dynamically created are treated as eval sources.
  // We detect these by looking at whether there was another script on the stack
  // when the source was created.
  if (
    (introType == "scriptElement" || introType == "importedModule") &&
    source.introductionScript
  ) {
    return true;
  }

  // These are all the sources that are essentially eval-ed (either
  // by calling eval or passing a string to one of these functions).
  return (
    introType === "eval" ||
    introType === "debugger eval" ||
    introType === "Function" ||
    introType === "eventHandler" ||
    introType === "setTimeout" ||
    introType === "setInterval"
  );
}

exports.isEvalSource = isEvalSource;

const windowsDrive = /^([a-zA-Z]:)/;

function getSourceURL(source, window) {
  // Some eval sources have URLs, but we want to explcitly ignore those because
  // they are generally useless strings like "eval" or "debugger eval code".
  const resourceURL =
    ((!isEvalSource(source) && source.url) || "").split(" -> ").pop() || null;

  // A "//# sourceURL=" pragma should basically be treated as a source file's
  // full URL, so that is what we want to use as the base if it is present.
  // If this is not an absolute URL, this will mean the maps in the file
  // will not have a valid base URL, but that is up to tooling that
  let result = resolveSourceURL(source.displayURL, window);
  if (!result) {
    result = resolveSourceURL(resourceURL, window) || resourceURL;

    // In XPCShell tests, the source URL isn't actually a URL, it's a file path.
    // That causes issues because "C:/folder/file.js" is parsed as a URL with
    // "c:" as the URL scheme, which causes the drive letter to be unexpectedly
    // lower-cased when the parsed URL is re-serialized. To avoid that, we
    // detect that case and re-uppercase it again. This is a bit gross and
    // ideally it seems like XPCShell tests should use file:// URLs for files,
    // but alas they do not.
    if (
      resourceURL &&
      resourceURL.match(windowsDrive) &&
      result.slice(0, 2) == resourceURL.slice(0, 2).toLowerCase()
    ) {
      result = resourceURL.slice(0, 2) + result.slice(2);
    }
  }

  return result;
}

/**
 * A SourceActor provides information about the source of a script. Source
 * actors are 1:1 with Debugger.Source objects.
 *
 * @param Debugger.Source source
 *        The source object we are representing.
 * @param ThreadActor thread
 *        The current thread actor.
 * @param Boolean isInlineSource
 *        Optional. True if this is an inline source from a HTML or XUL page.
 * @param String contentType
 *        Optional. The content type of this source, if immediately available.
 */
const SourceActor = ActorClassWithSpec(sourceSpec, {
  typeName: "source",

  initialize: function({ source, thread, isInlineSource, contentType }) {
    Actor.prototype.initialize.call(this, thread.conn);

    this._threadActor = thread;
    this._url = undefined;
    this._source = source;
    this._contentType = contentType;
    this._isInlineSource = isInlineSource;
    this._startLineColumnDisplacement = null;

    this.source = this.source.bind(this);
    this._getSourceText = this._getSourceText.bind(this);

    this._init = null;
  },

  get isInlineSource() {
    return this._isInlineSource;
  },

  get threadActor() {
    return this._threadActor;
  },
  get sources() {
    return this._threadActor.sources;
  },
  get dbg() {
    return this.threadActor.dbg;
  },
  get breakpointActorMap() {
    return this.threadActor.breakpointActorMap;
  },
  get url() {
    if (this._url === undefined) {
      this._url = getSourceURL(this._source, this.threadActor._parent.window);
    }
    return this._url;
  },

  get extensionName() {
    if (this._extensionName === undefined) {
      this._extensionName = null;

      // Cu is not available for workers and so we are not able to get a
      // WebExtensionPolicy object
      if (!isWorker && this.url) {
        try {
          const extURI = Services.io.newURI(this.url);
          if (extURI) {
            const policy = WebExtensionPolicy.getByURI(extURI);
            if (policy) {
              this._extensionName = policy.name;
            }
          }
        } catch (e) {
          // Ignore
        }
      }
    }

    return this._extensionName;
  },

  form: function() {
    const source = this._source;

    return {
      actor: this.actorID,
      extensionName: this.extensionName,
      url: this.url,
      isBlackBoxed: this.threadActor.sources.isBlackBoxed(this.url),
      sourceMapBaseURL: getSourcemapBaseURL(
        this.url,
        this.threadActor._parent.window
      ),
      sourceMapURL: source.sourceMapURL,
      introductionType: source.introductionType,
    };
  },

  destroy: function() {
    const parent = this.getParent();
    if (parent && parent.sourceActors) {
      delete parent.sourceActors[this.actorID];
    }
    Actor.prototype.destroy.call(this);
  },

  get isWasm() {
    return this._source.introductionType === "wasm";
  },

  _getSourceText: async function() {
    const toResolvedContent = t => ({
      content: t,
      contentType: this._contentType,
    });

    if (this.isWasm) {
      const wasm = this._source.binary;
      const buffer = wasm.buffer;
      assert(
        wasm.byteOffset === 0 && wasm.byteLength === buffer.byteLength,
        "Typed array from wasm source binary must cover entire buffer"
      );
      return toResolvedContent(buffer);
    }

    // Use `source.text` if it exists, is not the "no source" string, and
    // the content type of the source is JavaScript or it is synthesized
    // wasm. It will be "no source" if the Debugger API wasn't able to load
    // the source because sources were discarded
    // (javascript.options.discardSystemSource == true). Re-fetch non-JS
    // sources to get the contentType from the headers.
    if (
      this._source.text !== "[no source]" &&
      this._contentType &&
      (this._contentType.includes("javascript") ||
        this._contentType === "text/wasm")
    ) {
      return toResolvedContent(this.actualText());
    }

    const result = await this.sources.urlContents(
      this.url,
      /* partial */ false,
      /* canUseCache */ this.isInlineSource
    );

    // Record the contentType we just learned during fetching
    this._contentType = result.contentType;

    return result;
  },

  // Get the actual text of this source, padded so that line numbers will match
  // up with the source itself.
  actualText() {
    // If the source doesn't start at line 1, line numbers in the client will
    // not match up with those in the source. Pad the text with blank lines to
    // fix this. This can show up for sources associated with inline scripts
    // in HTML created via document.write() calls: the script's source line
    // number is relative to the start of the written HTML, but we show the
    // source's content by itself.
    const padding = this._source.startLine
      ? "\n".repeat(this._source.startLine - 1)
      : "";
    return padding + this._source.text;
  },

  // Return whether the specified fetched contents includes the actual text of
  // this source in the expected position.
  contentMatches(fileContents) {
    const lineBreak = /\r\n?|\n|\u2028|\u2029/;
    const contentLines = fileContents.content.split(lineBreak);
    const sourceLines = this._source.text.split(lineBreak);
    let line = this._source.startLine - 1;
    for (const sourceLine of sourceLines) {
      const contentLine = contentLines[line++] || "";
      if (!contentLine.includes(sourceLine)) {
        return false;
      }
    }
    return true;
  },

  getBreakableLines: async function() {
    const positions = await this.getBreakpointPositions();
    const lines = new Set();
    for (const position of positions) {
      if (!lines.has(position.line)) {
        lines.add(position.line);
      }
    }

    return Array.from(lines);
  },

  // For inline <script> tags in HTML pages, the column numbers of the start
  // line are relative to the column immediately after the opening <script> tag,
  // rather than the start of the line itself. Calculate the start line and any
  // column displacement from the start of that line in the HTML file.
  _getStartLineColumnDisplacement() {
    if (this._startLineColumnDisplacement) {
      return this._startLineColumnDisplacement;
    }

    // Allow fetching the partial contents of the HTML file. When getting the
    // displacement to install breakpoints on an inline source that just
    // appeared, we don't expect the HTML file to be completely loaded, and if
    // we wait for it to load then the script will have already started running.
    // Fetching the partial contents will only return a promise if we haven't
    // seen any data for the file, which will only be the case when the debugger
    // attaches to an existing page. In this case we don't need to get the
    // displacement synchronously, so it's OK if we yield to the event loop
    // while the promise resolves.
    const fileContents = this.sources.urlContents(
      this.url,
      /* partial */ true,
      /* canUseCache */ this.isInlineSource
    );
    if (fileContents.then) {
      return fileContents.then(contents =>
        this._setStartLineColumnDisplacement(contents)
      );
    }
    return this._setStartLineColumnDisplacement(fileContents);
  },

  _setStartLineColumnDisplacement(fileContents) {
    const d = this._calculateStartLineColumnDisplacement(fileContents);
    this._startLineColumnDisplacement = d;
    return d;
  },

  _calculateStartLineColumnDisplacement(fileContents) {
    const startLine = this._source.startLine;

    const lineBreak = /\r\n?|\n|\u2028|\u2029/;
    const fileStartLine =
      fileContents.content.split(lineBreak)[startLine - 1] || "";

    const sourceContents = this._source.text;

    if (lineBreak.test(sourceContents)) {
      // The inline script must end the HTML file's line.
      const firstLine = sourceContents.split(lineBreak)[0];
      if (firstLine.length && fileStartLine.endsWith(firstLine)) {
        const column = fileStartLine.length - firstLine.length;
        return { startLine, column };
      }
      return {};
    }

    // The inline script could be anywhere on the line. Search for its
    // contents in the line's text. This is a best-guess method and may return
    // the wrong result if the text appears multiple times on the line, but
    // the result should make some sense to the user in any case.
    const column = fileStartLine.indexOf(sourceContents);
    if (column != -1) {
      return { startLine, column };
    }
    return {};
  },

  // If a { line, column } location is on the starting line of an inline source,
  // adjust it upwards or downwards (per |upward|) according to the starting
  // column displacement.
  _adjustInlineScriptLocation(location, upward) {
    if (!this._isInlineSource) {
      return location;
    }

    const info = this._getStartLineColumnDisplacement();
    if (info.then) {
      return info.then(i =>
        this._adjustInlineScriptLocationFromDisplacement(i, location, upward)
      );
    }
    return this._adjustInlineScriptLocationFromDisplacement(
      info,
      location,
      upward
    );
  },

  _adjustInlineScriptLocationFromDisplacement(info, location, upward) {
    const { line, column } = location;
    if (this._startLineColumnDisplacement.startLine == line) {
      let displacement = this._startLineColumnDisplacement.column;
      if (!upward) {
        displacement = -displacement;
      }
      return { line, column: column + displacement };
    }
    return location;
  },

  // Get all toplevel scripts in the source. Transitive child scripts must be
  // found by traversing the child script tree.
  _getTopLevelDebuggeeScripts() {
    if (this._scripts) {
      return this._scripts;
    }

    let scripts = this.dbg.findScripts({ source: this._source });

    if (!this.isWasm) {
      // There is no easier way to get the top-level scripts right now, so
      // we have to build that up the list manually.
      // Note: It is not valid to simply look for scripts where
      // `.isFunction == false` because a source may have executed multiple
      // where some have been GCed and some have not (bug 1627712).
      const allScripts = new Set(scripts);
      for (const script of allScripts) {
        for (const child of script.getChildScripts()) {
          allScripts.delete(child);
        }
      }
      scripts = [...allScripts];
    }

    this._scripts = scripts;
    return scripts;
  },

  resetDebuggeeScripts() {
    this._scripts = null;
  },

  // Get toplevel scripts which contain all breakpoint positions for the source.
  // This is different from _scripts if we detected that some scripts have been
  // GC'ed and reparsed the source contents.
  _getTopLevelBreakpointPositionScripts() {
    if (this._breakpointPositionScripts) {
      return this._breakpointPositionScripts;
    }

    let scripts = this._getTopLevelDebuggeeScripts();

    // We need to find all breakpoint positions, even if scripts associated with
    // this source have been GC'ed. We detect this by looking for a script which
    // does not have a function: a source will typically have a top level
    // non-function script. If this top level script still exists, then it keeps
    // all its child scripts alive and we will find all breakpoint positions by
    // scanning the existing scripts. If the top level script has been GC'ed
    // then we won't find its breakpoint positions, and inner functions may have
    // been GC'ed as well. In this case we reparse the source and generate a new
    // and complete set of scripts to look for the breakpoint positions.
    // Note that in some cases like "new Function(stuff)" there might not be a
    // top level non-function script, but if there is a non-function script then
    // it must be at the top level and will keep all other scripts in the source
    // alive.
    if (!this.isWasm && !scripts.some(script => !script.isFunction)) {
      let newScript;
      try {
        newScript = this._source.reparse();
      } catch (e) {
        // reparse() will throw if the source is not valid JS. This can happen
        // if this source is the resurrection of a GC'ed source and there are
        // parse errors in the refetched contents.
      }
      if (newScript) {
        scripts = [newScript];
      }
    }

    this._breakpointPositionScripts = scripts;
    return scripts;
  },

  // Get all scripts in this source that might include content in the range
  // specified by the given query.
  _findDebuggeeScripts(query, forBreakpointPositions) {
    const scripts = forBreakpointPositions
      ? this._getTopLevelBreakpointPositionScripts()
      : this._getTopLevelDebuggeeScripts();

    const {
      start: { line: startLine = 0, column: startColumn = 0 } = {},
      end: { line: endLine = Infinity, column: endColumn = Infinity } = {},
    } = query || {};

    const rv = [];
    addMatchingScripts(scripts);
    return rv;

    function scriptMatches(script) {
      // These tests are approximate, as we can't easily get the script's end
      // column.
      let lineCount;
      try {
        lineCount = script.lineCount;
      } catch (err) {
        // Accessing scripts which were optimized out during parsing can throw
        // an exception. Tolerate these so that we can still get positions for
        // other scripts in the source.
        return false;
      }

      if (
        script.startLine > endLine ||
        script.startLine + lineCount <= startLine ||
        (script.startLine == endLine && script.startColumn > endColumn)
      ) {
        return false;
      }

      if (
        lineCount == 1 &&
        script.startLine == startLine &&
        script.startColumn + script.sourceLength <= startColumn
      ) {
        return false;
      }

      return true;
    }

    function addMatchingScripts(childScripts) {
      for (const script of childScripts) {
        if (scriptMatches(script)) {
          rv.push(script);
          if (script.format === "js") {
            addMatchingScripts(script.getChildScripts());
          }
        }
      }
    }
  },

  getBreakpointPositions: async function(query) {
    const scripts = this._findDebuggeeScripts(
      query,
      /* forBreakpoiontPositions */ true
    );

    const positions = [];
    for (const script of scripts) {
      await this._addScriptBreakpointPositions(query, script, positions);
    }

    return (
      positions
        // Sort the items by location.
        .sort((a, b) => {
          const lineDiff = a.line - b.line;
          return lineDiff === 0 ? a.column - b.column : lineDiff;
        })
    );
  },

  async _addScriptBreakpointPositions(query, script, positions) {
    const {
      start: { line: startLine = 0, column: startColumn = 0 } = {},
      end: { line: endLine = Infinity, column: endColumn = Infinity } = {},
    } = query || {};

    const offsets = script.getPossibleBreakpoints();
    for (const { lineNumber, columnNumber } of offsets) {
      if (
        lineNumber < startLine ||
        (lineNumber === startLine && columnNumber < startColumn) ||
        lineNumber > endLine ||
        (lineNumber === endLine && columnNumber >= endColumn)
      ) {
        continue;
      }

      // Adjust columns according to any inline script start column, so that
      // column breakpoints show up correctly in the UI.
      const position = await this._adjustInlineScriptLocation(
        {
          line: lineNumber,
          column: columnNumber,
        },
        /* upward */ true
      );

      positions.push(position);
    }
  },

  getBreakpointPositionsCompressed: async function(query) {
    const items = await this.getBreakpointPositions(query);
    const compressed = {};
    for (const { line, column } of items) {
      if (!compressed[line]) {
        compressed[line] = [];
      }
      compressed[line].push(column);
    }
    return compressed;
  },

  /**
   * Handler for the "onSource" packet.
   * @return Object
   *         The return of this function contains a field `contentType`, and
   *         a field `source`. `source` can either be an ArrayBuffer or
   *         a LongString.
   */
  source: function() {
    return Promise.resolve(this._init)
      .then(this._getSourceText)
      .then(({ content, contentType }) => {
        if (
          typeof content === "object" &&
          content &&
          content.constructor &&
          content.constructor.name === "ArrayBuffer"
        ) {
          return {
            source: new ArrayBufferActor(this.threadActor.conn, content),
            contentType,
          };
        }

        return {
          source: new LongStringActor(this.threadActor.conn, content),
          contentType,
        };
      })
      .catch(error => {
        reportError(error, "Got an exception during SA_onSource: ");
        throw new Error(
          "Could not load the source for " +
            this.url +
            ".\n" +
            DevToolsUtils.safeErrorString(error)
        );
      });
  },

  /**
   * Handler for the "blackbox" packet.
   */
  blackbox: function(range) {
    this.threadActor.sources.blackBox(this.url, range);
    if (
      this.threadActor.state == "paused" &&
      this.threadActor.youngestFrame &&
      this.threadActor.youngestFrame.script.url == this.url
    ) {
      return true;
    }
    return false;
  },

  /**
   * Handler for the "unblackbox" packet.
   */
  unblackbox: function(range) {
    this.threadActor.sources.unblackBox(this.url, range);
  },

  /**
   * Handler for the "setPausePoints" packet.
   *
   * @param Array pausePoints
   *        A dictionary of pausePoint objects
   *
   *        type PausePoints = {
   *          line: {
   *            column: { break?: boolean, step?: boolean }
   *          }
   *        }
   */
  setPausePoints: function(pausePoints) {
    const uncompressed = {};
    const points = {
      0: {},
      1: { break: true },
      2: { step: true },
      3: { break: true, step: true },
    };

    for (const line in pausePoints) {
      uncompressed[line] = {};
      for (const col in pausePoints[line]) {
        uncompressed[line][col] = points[pausePoints[line][col]];
      }
    }

    this.pausePoints = uncompressed;
  },

  /*
   * Ensure the given BreakpointActor is set as a breakpoint handler on all
   * scripts that match its location in the generated source.
   *
   * @param BreakpointActor actor
   *        The BreakpointActor to be set as a breakpoint handler.
   *
   * @returns A Promise that resolves to the given BreakpointActor.
   */
  applyBreakpoint: async function(actor) {
    let { line, column } = actor.location;

    // Find all entry points that correspond to the given location.
    const entryPoints = [];
    if (column === undefined) {
      // Find all scripts that match the given source actor and line
      // number.
      const query = { start: { line }, end: { line } };
      const scripts = this._findDebuggeeScripts(query).filter(
        script => !actor.hasScript(script)
      );

      // This is a line breakpoint, so we add a breakpoint on the first
      // breakpoint on the line.
      const lineMatches = [];
      for (const script of scripts) {
        const possibleBreakpoints = script.getPossibleBreakpoints({ line });
        for (const possibleBreakpoint of possibleBreakpoints) {
          lineMatches.push({ ...possibleBreakpoint, script });
        }
      }
      lineMatches.sort((a, b) => a.columnNumber - b.columnNumber);

      if (lineMatches.length > 0) {
        // A single Debugger.Source may have _multiple_ Debugger.Scripts
        // at the same position from multiple evaluations of the source,
        // so we explicitly want to take all of the matches for the matched
        // column number.
        const firstColumn = lineMatches[0].columnNumber;
        const firstColumnMatches = lineMatches.filter(
          m => m.columnNumber === firstColumn
        );

        for (const { script, offset } of firstColumnMatches) {
          entryPoints.push({ script, offsets: [offset] });
        }
      }
    } else {
      // Adjust columns according to any inline script start column, to undo
      // the adjustment performed when sending the breakpoint to the client and
      // allow the breakpoint to be set correctly in the source (which treats
      // the location after the <script> tag as column 0).
      let adjusted = this._adjustInlineScriptLocation(
        { line, column },
        /* upward */ false
      );
      if (adjusted.then) {
        adjusted = await adjusted;
      }
      line = adjusted.line;
      column = adjusted.column;

      // Find all scripts that match the given source actor, line,
      // and column number.
      const query = { start: { line, column }, end: { line, column } };
      const scripts = this._findDebuggeeScripts(query).filter(
        script => !actor.hasScript(script)
      );

      for (const script of scripts) {
        // Check to see if the script contains a breakpoint position at
        // this line and column.
        const possibleBreakpoint = script
          .getPossibleBreakpoints({
            line,
            minColumn: column,
            maxColumn: column + 1,
          })
          .pop();

        if (possibleBreakpoint) {
          const { offset } = possibleBreakpoint;
          entryPoints.push({ script, offsets: [offset] });
        }
      }
    }

    setBreakpointAtEntryPoints(actor, entryPoints);
  },
});

exports.SourceActor = SourceActor;