/* 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 {
  Component,
  createFactory,
} = require("resource://devtools/client/shared/vendor/react.js");
const dom = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
const {
  assert,
  safeErrorString,
} = require("resource://devtools/shared/DevToolsUtils.js");
const Census = createFactory(
  require("resource://devtools/client/memory/components/Census.js")
);
const CensusHeader = createFactory(
  require("resource://devtools/client/memory/components/CensusHeader.js")
);
const DominatorTree = createFactory(
  require("resource://devtools/client/memory/components/DominatorTree.js")
);
const DominatorTreeHeader = createFactory(
  require("resource://devtools/client/memory/components/DominatorTreeHeader.js")
);
const TreeMap = createFactory(
  require("resource://devtools/client/memory/components/TreeMap.js")
);
const HSplitBox = createFactory(
  require("resource://devtools/client/shared/components/HSplitBox.js")
);
const Individuals = createFactory(
  require("resource://devtools/client/memory/components/Individuals.js")
);
const IndividualsHeader = createFactory(
  require("resource://devtools/client/memory/components/IndividualsHeader.js")
);
const ShortestPaths = createFactory(
  require("resource://devtools/client/memory/components/ShortestPaths.js")
);
const {
  getStatusTextFull,
  L10N,
} = require("resource://devtools/client/memory/utils.js");
const {
  snapshotState: states,
  diffingState,
  viewState,
  censusState,
  treeMapState,
  dominatorTreeState,
  individualsState,
} = require("resource://devtools/client/memory/constants.js");
const models = require("resource://devtools/client/memory/models.js");
const { snapshot: snapshotModel, diffingModel } = models;

/**
 * Get the app state's current state atom.
 *
 * @see the relevant state string constants in `../constants.js`.
 *
 * @param {models.view} view
 * @param {snapshotModel} snapshot
 * @param {diffingModel} diffing
 * @param {individualsModel} individuals
 *
 * @return {snapshotState|diffingState|dominatorTreeState}
 */
function getState(view, snapshot, diffing, individuals) {
  switch (view.state) {
    case viewState.CENSUS:
      return snapshot.census ? snapshot.census.state : snapshot.state;

    case viewState.DIFFING:
      return diffing.state;

    case viewState.TREE_MAP:
      return snapshot.treeMap ? snapshot.treeMap.state : snapshot.state;

    case viewState.DOMINATOR_TREE:
      return snapshot.dominatorTree
        ? snapshot.dominatorTree.state
        : snapshot.state;

    case viewState.INDIVIDUALS:
      return individuals.state;
  }

  assert(false, `Unexpected view state: ${view.state}`);
  return null;
}

/**
 * Return true if we should display a status message when we are in the given
 * state. Return false otherwise.
 *
 * @param {snapshotState|diffingState|dominatorTreeState} state
 * @param {models.view} view
 * @param {snapshotModel} snapshot
 *
 * @returns {Boolean}
 */
function shouldDisplayStatus(state, view, snapshot) {
  switch (state) {
    case states.IMPORTING:
    case states.SAVING:
    case states.SAVED:
    case states.READING:
    case censusState.SAVING:
    case treeMapState.SAVING:
    case diffingState.SELECTING:
    case diffingState.TAKING_DIFF:
    case dominatorTreeState.COMPUTING:
    case dominatorTreeState.COMPUTED:
    case dominatorTreeState.FETCHING:
    case individualsState.COMPUTING_DOMINATOR_TREE:
    case individualsState.FETCHING:
      return true;
  }
  return view.state === viewState.DOMINATOR_TREE && !snapshot.dominatorTree;
}

/**
 * Get the status text to display for the given state.
 *
 * @param {snapshotState|diffingState|dominatorTreeState} state
 * @param {diffingModel} diffing
 *
 * @returns {String}
 */
function getStateStatusText(state, diffing) {
  if (state === diffingState.SELECTING) {
    return L10N.getStr(
      diffing.firstSnapshotId === null
        ? "diffing.prompt.selectBaseline"
        : "diffing.prompt.selectComparison"
    );
  }

  return getStatusTextFull(state);
}

/**
 * Given that we should display a status message, return true if we should also
 * display a throbber along with the status message. Return false otherwise.
 *
 * @param {diffingModel} diffing
 *
 * @returns {Boolean}
 */
function shouldDisplayThrobber(diffing) {
  return !diffing || diffing.state !== diffingState.SELECTING;
}

/**
 * Get the current state's error, or return null if there is none.
 *
 * @param {snapshotModel} snapshot
 * @param {diffingModel} diffing
 * @param {individualsModel} individuals
 *
 * @returns {Error|null}
 */
function getError(snapshot, diffing, individuals) {
  if (diffing) {
    if (diffing.state === diffingState.ERROR) {
      return diffing.error;
    }
    if (diffing.census === censusState.ERROR) {
      return diffing.census.error;
    }
  }

  if (snapshot) {
    if (snapshot.state === states.ERROR) {
      return snapshot.error;
    }

    if (snapshot.census === censusState.ERROR) {
      return snapshot.census.error;
    }

    if (snapshot.treeMap === treeMapState.ERROR) {
      return snapshot.treeMap.error;
    }

    if (
      snapshot.dominatorTree &&
      snapshot.dominatorTree.state === dominatorTreeState.ERROR
    ) {
      return snapshot.dominatorTree.error;
    }
  }

  if (individuals && individuals.state === individualsState.ERROR) {
    return individuals.error;
  }

  return null;
}

/**
 * Main view for the memory tool.
 *
 * The Heap component contains several panels for different states; an initial
 * state of only a button to take a snapshot, loading states, the census view
 * tree, the dominator tree, etc.
 */
class Heap extends Component {
  static get propTypes() {
    return {
      onSnapshotClick: PropTypes.func.isRequired,
      onLoadMoreSiblings: PropTypes.func.isRequired,
      onCensusExpand: PropTypes.func.isRequired,
      onCensusCollapse: PropTypes.func.isRequired,
      onDominatorTreeExpand: PropTypes.func.isRequired,
      onDominatorTreeCollapse: PropTypes.func.isRequired,
      onCensusFocus: PropTypes.func.isRequired,
      onDominatorTreeFocus: PropTypes.func.isRequired,
      onShortestPathsResize: PropTypes.func.isRequired,
      snapshot: snapshotModel,
      onViewSourceInDebugger: PropTypes.func.isRequired,
      onPopView: PropTypes.func.isRequired,
      individuals: models.individuals,
      onViewIndividuals: PropTypes.func.isRequired,
      onFocusIndividual: PropTypes.func.isRequired,
      diffing: diffingModel,
      view: models.view.isRequired,
      sizes: PropTypes.object.isRequired,
    };
  }

  constructor(props) {
    super(props);
    this._renderHeapView = this._renderHeapView.bind(this);
    this._renderInitial = this._renderInitial.bind(this);
    this._renderStatus = this._renderStatus.bind(this);
    this._renderError = this._renderError.bind(this);
    this._renderCensus = this._renderCensus.bind(this);
    this._renderTreeMap = this._renderTreeMap.bind(this);
    this._renderIndividuals = this._renderIndividuals.bind(this);
    this._renderDominatorTree = this._renderDominatorTree.bind(this);
  }

  /**
   * Render the heap view's container panel with the given contents inside of
   * it.
   *
   * @param {snapshotState|diffingState|dominatorTreeState} state
   * @param {...Any} contents
   */
  _renderHeapView(state, ...contents) {
    return dom.div(
      {
        id: "heap-view",
        "data-state": state,
      },
      dom.div(
        {
          className: "heap-view-panel",
          "data-state": state,
        },
        ...contents
      )
    );
  }

  _renderInitial(onSnapshotClick) {
    return this._renderHeapView(
      "initial",
      dom.button(
        {
          className: "devtools-button take-snapshot",
          onClick: onSnapshotClick,
          "data-standalone": true,
        },
        L10N.getStr("take-snapshot")
      )
    );
  }

  _renderStatus(state, statusText, diffing) {
    let throbber = "";
    if (shouldDisplayThrobber(diffing)) {
      throbber = "devtools-throbber";
    }

    return this._renderHeapView(
      state,
      dom.span(
        {
          className: `snapshot-status ${throbber}`,
        },
        statusText
      )
    );
  }

  _renderError(state, statusText, error) {
    return this._renderHeapView(
      state,
      dom.span({ className: "snapshot-status error" }, statusText),
      dom.pre({}, safeErrorString(error))
    );
  }

  _renderCensus(
    state,
    census,
    diffing,
    onViewSourceInDebugger,
    onViewIndividuals
  ) {
    assert(
      census.report,
      "Should not render census that does not have a report"
    );

    if (!census.report.children) {
      const censusFilterMsg = census.filter
        ? L10N.getStr("heapview.none-match")
        : L10N.getStr("heapview.empty");
      const msg = diffing
        ? L10N.getStr("heapview.no-difference")
        : censusFilterMsg;
      return this._renderHeapView(state, dom.div({ className: "empty" }, msg));
    }

    const contents = [];

    if (
      census.display.breakdown.by === "allocationStack" &&
      census.report.children &&
      census.report.children.length === 1 &&
      census.report.children[0].name === "noStack"
    ) {
      contents.push(
        dom.div(
          { className: "error no-allocation-stacks" },
          L10N.getStr("heapview.noAllocationStacks")
        )
      );
    }

    contents.push(CensusHeader({ diffing }));
    contents.push(
      Census({
        onViewSourceInDebugger,
        onViewIndividuals,
        diffing,
        census,
        onExpand: node => this.props.onCensusExpand(census, node),
        onCollapse: node => this.props.onCensusCollapse(census, node),
        onFocus: node => this.props.onCensusFocus(census, node),
      })
    );

    return this._renderHeapView(state, ...contents);
  }

  _renderTreeMap(state, treeMap) {
    return this._renderHeapView(state, TreeMap({ treeMap }));
  }

  _renderIndividuals(
    state,
    individuals,
    dominatorTree,
    onViewSourceInDebugger
  ) {
    assert(
      individuals.state === individualsState.FETCHED,
      "Should have fetched individuals"
    );
    assert(dominatorTree?.root, "Should have a dominator tree and its root");

    const tree = dom.div(
      {
        className: "vbox",
        style: {
          overflowY: "auto",
        },
      },
      IndividualsHeader(),
      Individuals({
        individuals,
        dominatorTree,
        onViewSourceInDebugger,
        onFocus: this.props.onFocusIndividual,
      })
    );

    const shortestPaths = ShortestPaths({
      graph: individuals.focused ? individuals.focused.shortestPaths : null,
    });

    return this._renderHeapView(
      state,
      dom.div(
        { className: "hbox devtools-toolbar" },
        dom.label(
          { id: "pop-view-button-label" },
          dom.button(
            {
              id: "pop-view-button",
              className: "devtools-button",
              onClick: this.props.onPopView,
            },
            L10N.getStr("toolbar.pop-view")
          ),
          L10N.getStr("toolbar.pop-view.label")
        ),
        dom.span(
          { className: "toolbar-text" },
          L10N.getStr("toolbar.viewing-individuals")
        )
      ),
      HSplitBox({
        start: tree,
        end: shortestPaths,
        startWidth: this.props.sizes.shortestPathsSize,
        onResize: this.props.onShortestPathsResize,
      })
    );
  }

  _renderDominatorTree(
    state,
    onViewSourceInDebugger,
    dominatorTree,
    onLoadMoreSiblings
  ) {
    const tree = dom.div(
      {
        className: "vbox",
        style: {
          overflowY: "auto",
        },
      },
      DominatorTreeHeader(),
      DominatorTree({
        onViewSourceInDebugger,
        dominatorTree,
        onLoadMoreSiblings,
        onExpand: this.props.onDominatorTreeExpand,
        onCollapse: this.props.onDominatorTreeCollapse,
        onFocus: this.props.onDominatorTreeFocus,
      })
    );

    const shortestPaths = ShortestPaths({
      graph: dominatorTree.focused ? dominatorTree.focused.shortestPaths : null,
    });

    return this._renderHeapView(
      state,
      HSplitBox({
        start: tree,
        end: shortestPaths,
        startWidth: this.props.sizes.shortestPathsSize,
        onResize: this.props.onShortestPathsResize,
      })
    );
  }

  render() {
    const {
      snapshot,
      diffing,
      onSnapshotClick,
      onLoadMoreSiblings,
      onViewSourceInDebugger,
      onViewIndividuals,
      individuals,
      view,
    } = this.props;

    if (!diffing && !snapshot && !individuals) {
      return this._renderInitial(onSnapshotClick);
    }

    const state = getState(view, snapshot, diffing, individuals);
    const statusText = getStateStatusText(state, diffing);

    if (shouldDisplayStatus(state, view, snapshot)) {
      return this._renderStatus(state, statusText, diffing);
    }

    const error = getError(snapshot, diffing, individuals);
    if (error) {
      return this._renderError(state, statusText, error);
    }

    if (view.state === viewState.CENSUS || view.state === viewState.DIFFING) {
      const census =
        view.state === viewState.CENSUS ? snapshot.census : diffing.census;
      if (!census) {
        return this._renderStatus(state, statusText, diffing);
      }
      return this._renderCensus(
        state,
        census,
        diffing,
        onViewSourceInDebugger,
        onViewIndividuals
      );
    }

    if (view.state === viewState.TREE_MAP) {
      return this._renderTreeMap(state, snapshot.treeMap);
    }

    if (view.state === viewState.INDIVIDUALS) {
      assert(
        individuals.state === individualsState.FETCHED,
        "Should have fetched the individuals -- " +
          "other states are rendered as statuses"
      );
      return this._renderIndividuals(
        state,
        individuals,
        individuals.dominatorTree,
        onViewSourceInDebugger
      );
    }

    assert(
      view.state === viewState.DOMINATOR_TREE,
      "If we aren't in progress, looking at a census, or diffing, then we " +
        "must be looking at a dominator tree"
    );
    assert(!diffing, "Should not have diffing");
    assert(snapshot.dominatorTree, "Should have a dominator tree");

    return this._renderDominatorTree(
      state,
      onViewSourceInDebugger,
      snapshot.dominatorTree,
      onLoadMoreSiblings
    );
  }
}

module.exports = Heap;
