import {
  type DocMode,
  DocModes,
  type ParagraphBlockModel,
  type ReferenceInfo,
} from '@blocksuite/affine-model';
import {
  BLOCK_ID_ATTR,
  type BlockComponent,
  BlockSelection,
  type EditorHost,
  type TextRangePoint,
  TextSelection,
} from '@blocksuite/block-std';
import { BlockSuiteError, ErrorCode } from '@blocksuite/global/exceptions';
import { assertExists } from '@blocksuite/global/utils';
import {
  type BlockModel,
  type BlockSnapshot,
  type DeltaOperation,
  fromJSON,
  type JobMiddleware,
  type SliceSnapshot,
  type Text,
} from '@blocksuite/store';
import * as Y from 'yjs';

import { REFERENCE_NODE } from '../../consts';
import { ImageSelection } from '../../selection';
import {
  ParseDocUrlProvider,
  type ParseDocUrlService,
  TelemetryProvider,
} from '../../services';
import type { AffineTextAttributes } from '../../types';
import { matchFlavours, referenceToNode } from '../../utils';

function findLastMatchingNode(
  root: BlockSnapshot[],
  fn: (node: BlockSnapshot) => boolean
): BlockSnapshot | null {
  let lastMatchingNode: BlockSnapshot | null = null;

  function traverse(node: BlockSnapshot) {
    if (fn(node)) {
      lastMatchingNode = node;
    }
    if (node.children) {
      for (const child of node.children) {
        traverse(child);
      }
    }
  }

  root.forEach(traverse);
  return lastMatchingNode;
}

// find last child that has text as prop
const findLast = (snapshot: SliceSnapshot): BlockSnapshot | null => {
  return findLastMatchingNode(snapshot.content, node => !!node.props.text);
};

class PointState {
  private readonly _blockFromPath = (path: string) => {
    const block = this.std.view.getBlock(path);
    assertExists(block);
    return block;
  };

  readonly block: BlockComponent;

  readonly model: BlockModel;

  readonly text: Text;

  constructor(
    readonly std: EditorHost['std'],
    readonly point: TextRangePoint
  ) {
    this.block = this._blockFromPath(point.blockId);
    this.model = this.block.model;
    const text = this.model.text;
    if (!text) {
      console.error(this.point);
      throw new BlockSuiteError(
        ErrorCode.TransformerError,
        'Text point without text model'
      );
    }
    this.text = text;
  }
}

class PasteTr {
  private readonly _getDeltas = () => {
    const firstTextSnapshot = this._textFromSnapshot(this.firstSnapshot!);
    const lastTextSnapshot = this._textFromSnapshot(this.lastSnapshot!);
    const fromDelta = this.pointState.text.sliceToDelta(
      0,
      this.pointState.point.index
    );
    const toDelta = this.pointState.text.sliceToDelta(
      this.pointState.point.index + this.pointState.point.length,
      this.pointState.text.length
    );
    const firstDelta = firstTextSnapshot.delta;
    const lastDelta = lastTextSnapshot.delta;
    return {
      firstTextSnapshot,
      lastTextSnapshot,
      fromDelta,
      toDelta,
      firstDelta,
      lastDelta,
    };
  };

  private readonly _mergeCode = () => {
    const deltas: DeltaOperation[] = [{ retain: this.pointState.point.index }];
    this.snapshot.content.forEach((blockSnapshot, i) => {
      if (blockSnapshot.props.text) {
        const text = this._textFromSnapshot(blockSnapshot);
        if (i > 0) {
          deltas.push({ insert: '\n' });
        }
        deltas.push(...text.delta);
      }
    });
    this.pointState.text.applyDelta(deltas);
    this.snapshot.content = [];
  };

  private readonly _mergeMultiple = () => {
    this._updateFlavour();

    const { lastTextSnapshot, toDelta, firstDelta, lastDelta } =
      this._getDeltas();

    this.pointState.text.applyDelta([
      { retain: this.pointState.point.index },
      this.pointState.text.length - this.pointState.point.index > 0
        ? { delete: this.pointState.text.length - this.pointState.point.index }
        : {},
      ...firstDelta,
    ]);

    const removedFirstSnapshot = this.snapshot.content.shift();
    removedFirstSnapshot?.children.forEach(block => {
      this.snapshot.content.unshift(block);
    });
    this.pasteStartModelChildrenCount =
      removedFirstSnapshot?.children.length ?? 0;

    this._updateSnapshot();

    lastTextSnapshot.delta = [...lastDelta, ...toDelta];
  };

  private readonly _mergeSingle = () => {
    this._updateFlavour();
    const { firstDelta } = this._getDeltas();
    const { index, length } = this.pointState.point;

    // Pastes a link
    if (length && firstDelta.length === 1 && firstDelta[0].attributes?.link) {
      this.pointState.text.format(index, length, firstDelta[0].attributes);
    } else {
      const ops: DeltaOperation[] = [{ retain: index }];
      if (length) ops.push({ delete: length });
      ops.push(...firstDelta);

      this.pointState.text.applyDelta(ops);
    }

    this.snapshot.content.splice(0, 1);
    this._updateSnapshot();
  };

  private readonly _textFromSnapshot = (snapshot: BlockSnapshot) => {
    return (snapshot.props.text ?? { delta: [] }) as Record<
      'delta',
      DeltaOperation[]
    >;
  };

  private readonly _updateSnapshot = () => {
    if (this.snapshot.content.length === 0) {
      this.firstSnapshot = this.lastSnapshot = undefined;
      return;
    }
    this.firstSnapshot = this.snapshot.content[0];
    this.lastSnapshot = findLast(this.snapshot) ?? this.firstSnapshot;
  };

  private firstSnapshot?: BlockSnapshot;

  private readonly firstSnapshotIsPlainText: boolean;

  private readonly lastIndex: number;

  private lastSnapshot?: BlockSnapshot;

  private needCleanup = false;

  private pasteStartModelChildrenCount = 0;

  private readonly pointState: PointState;

  canMerge = () => {
    if (this.snapshot.content.length === 0) {
      return false;
    }
    if (!this.firstSnapshot!.props.text) {
      return false;
    }
    const firstTextSnapshot = this._textFromSnapshot(this.firstSnapshot!);
    const lastTextSnapshot = this._textFromSnapshot(this.lastSnapshot!);
    return (
      firstTextSnapshot &&
      lastTextSnapshot &&
      (this.pointState.text.length > 0 || this.firstSnapshotIsPlainText)
    );
  };

  convertToLinkedDoc = () => {
    const parseDocUrlService = this.std.getOptional(ParseDocUrlProvider);

    if (!parseDocUrlService) {
      return;
    }

    const linkToDocId = new Map<string, string | null>();

    for (const blockSnapshot of this.snapshot.content) {
      if (blockSnapshot.props.text) {
        const [delta, transformed] = this._transformLinkDelta(
          this._textFromSnapshot(blockSnapshot).delta,
          linkToDocId,
          parseDocUrlService
        );
        const model = this.std.doc.getBlock(blockSnapshot.id)?.model;
        if (transformed && model) {
          this.std.doc.captureSync();
          this.std.doc.transact(() => {
            const text = model.text as Text;
            text.clear();
            text.applyDelta(delta);
          });
        }
      }
    }

    const fromPointStateText = this.pointState.model.text;
    if (!fromPointStateText) {
      return;
    }
    const [delta, transformed] = this._transformLinkDelta(
      fromPointStateText.toDelta(),
      linkToDocId,
      parseDocUrlService
    );
    if (!transformed) {
      return;
    }
    this.std.doc.captureSync();
    this.std.doc.transact(() => {
      fromPointStateText.clear();
      fromPointStateText.applyDelta(delta);
    });
  };

  focusPasted = () => {
    const host = this.std.host;

    const cursorBlock =
      this.pointState.model.flavour === 'affine:code' || !this.lastSnapshot
        ? this.std.doc.getBlock(this.pointState.model.id)
        : this.std.doc.getBlock(this.lastSnapshot.id);
    if (!cursorBlock) {
      return;
    }
    const { model: cursorModel } = cursorBlock;

    host.updateComplete
      .then(() => {
        const target = this.std.host.querySelector<BlockComponent>(
          `[${BLOCK_ID_ATTR}="${cursorModel.id}"]`
        );
        if (!target) {
          return;
        }
        if (!cursorModel.text) {
          if (matchFlavours(cursorModel, ['affine:image'])) {
            const selection = this.std.selection.create(ImageSelection, {
              blockId: target.blockId,
            });
            this.std.selection.setGroup('note', [selection]);
            return;
          }
          const selection = this.std.selection.create(BlockSelection, {
            blockId: target.blockId,
          });
          this.std.selection.setGroup('note', [selection]);
          return;
        }
        const selection = this.std.selection.create(TextSelection, {
          from: {
            blockId: target.blockId,
            index: cursorModel.text ? this.lastIndex : 0,
            length: 0,
          },
          to: null,
        });
        this.std.selection.setGroup('note', [selection]);
      })
      .catch(console.error);
  };

  pasted = () => {
    if (!(this.needCleanup || this.pointState.text.length === 0)) {
      return;
    }

    if (this.lastSnapshot) {
      const lastModel = this.std.doc.getBlock(this.lastSnapshot.id)?.model;
      if (!lastModel) {
        return;
      }
      this.std.doc.moveBlocks(this.pointState.model.children, lastModel);
    }

    this.std.doc.moveBlocks(
      this.std.doc
        .getNexts(this.pointState.model.id)
        .slice(0, this.pasteStartModelChildrenCount),
      this.pointState.model
    );

    if (!this.firstSnapshotIsPlainText && this.pointState.text.length == 0) {
      this.std.doc.deleteBlock(this.pointState.model);
    }
  };

  constructor(
    readonly std: EditorHost['std'],
    readonly text: TextSelection,
    readonly snapshot: SliceSnapshot
  ) {
    const { from } = text;

    this.pointState = new PointState(std, from);

    this.firstSnapshot = snapshot.content[0];
    this.lastSnapshot = findLast(snapshot) ?? this.firstSnapshot;
    if (
      this.firstSnapshot !== this.lastSnapshot &&
      this.lastSnapshot.props.text &&
      !matchFlavours(this.pointState.model, ['affine:code'])
    ) {
      const text = fromJSON(this.lastSnapshot.props.text) as Text;
      const doc = new Y.Doc();
      const temp = doc.getMap('temp');
      temp.set('text', text.yText);
      this.lastIndex = text.length;
    } else {
      this.lastIndex =
        this.pointState.point.index +
        this.snapshot.content
          .map(snapshot =>
            this._textFromSnapshot(snapshot)
              .delta.map(op => {
                if (op.insert) {
                  return op.insert.length;
                } else if (op.delete) {
                  return -op.delete;
                } else {
                  return 0;
                }
              })
              .reduce((a, b) => a + b, 0)
          )
          .reduce((a, b) => a + b + 1, -1);
    }
    this.firstSnapshotIsPlainText =
      this.firstSnapshot.flavour === 'affine:paragraph' &&
      this.firstSnapshot.props.type === 'text';
  }

  private _transformLinkDelta(
    delta: DeltaOperation[],
    linkToDocId: Map<string, string | null>,
    parseDocUrlService: ParseDocUrlService
  ): [DeltaOperation[], boolean] {
    let transformed = false;
    const needToConvert = new Map<DeltaOperation, string>();
    for (const op of delta) {
      if (op.attributes?.link) {
        let docId = linkToDocId.get(op.attributes.link);
        if (!docId) {
          const searchResult = parseDocUrlService.parseDocUrl(
            op.attributes.link
          );
          if (searchResult) {
            const doc = this.std.workspace.getDoc(searchResult.docId);
            if (doc) {
              docId = doc.id;
              linkToDocId.set(op.attributes.link, doc.id);
            }
          }
        }
        if (docId) {
          needToConvert.set(op, docId);
        }
      }
    }
    const newDelta = delta.map(op => {
      if (!needToConvert.has(op)) {
        return { ...op };
      }

      const link = op.attributes?.link;

      if (!link) {
        return { ...op };
      }

      const pageId = needToConvert.get(op);

      if (!pageId) {
        // External link
        this.std.getOptional(TelemetryProvider)?.track('Link', {
          page: 'doc editor',
          category: 'pasted link',
          other: 'external link',
          type: 'link',
        });

        return { ...op };
      }

      const reference: AffineTextAttributes['reference'] = {
        pageId,
        type: 'LinkedPage',
      };
      // Title alias
      if (op.insert && op.insert !== REFERENCE_NODE && op.insert !== link) {
        reference.title = op.insert;
      }

      const extractedParams = extractSearchParams(link);
      const isLinkedBlock = extractedParams
        ? referenceToNode({ pageId, ...extractedParams })
        : false;

      Object.assign(reference, extractedParams);

      // Internal link
      this.std.getOptional(TelemetryProvider)?.track('LinkedDocCreated', {
        page: 'doc editor',
        category: 'pasted link',
        other: 'existing doc',
        type: isLinkedBlock ? 'block' : 'doc',
      });

      transformed = true;

      return {
        ...op,
        attributes: { reference },
        insert: REFERENCE_NODE,
      };
    });
    return [newDelta, transformed];
  }

  private _updateFlavour() {
    this.firstSnapshot!.flavour = this.pointState.model.flavour;
    if (this.firstSnapshot!.props.type) {
      this.firstSnapshot!.props.type = (
        this.pointState.model as ParagraphBlockModel
      ).type;
    }
  }

  merge() {
    if (this.pointState.model.flavour === 'affine:code') {
      this._mergeCode();
      return;
    }

    if (this.firstSnapshot === this.lastSnapshot) {
      this._mergeSingle();
      return;
    }

    this.needCleanup = true;
    this._mergeMultiple();
  }
}

function flatNote(snapshot: SliceSnapshot) {
  if (snapshot.content[0]?.flavour === 'affine:note') {
    snapshot.content = snapshot.content[0].children;
  }
}

export const pasteMiddleware = (std: EditorHost['std']): JobMiddleware => {
  return ({ slots }) => {
    let tr: PasteTr | undefined;
    slots.beforeImport.on(payload => {
      if (payload.type === 'slice') {
        const { snapshot } = payload;
        flatNote(snapshot);

        const text = std.selection.find(TextSelection);
        if (!text) {
          return;
        }
        tr = new PasteTr(std, text, payload.snapshot);
        if (tr.canMerge()) {
          tr.merge();
        }
      }
    });
    slots.afterImport.on(payload => {
      if (tr && payload.type === 'slice') {
        tr.pasted();
        tr.focusPasted();
        tr.convertToLinkedDoc();
      }
    });
  };
};

function extractSearchParams(link: string) {
  try {
    const url = new URL(link);
    const mode = url.searchParams.get('mode') as DocMode | undefined;

    if (mode && DocModes.includes(mode)) {
      const params: ReferenceInfo['params'] = { mode: mode as DocMode };
      const blockIds = url.searchParams
        .get('blockIds')
        ?.trim()
        .split(',')
        .map(id => id.trim())
        .filter(id => id.length);
      const elementIds = url.searchParams
        .get('elementIds')
        ?.trim()
        .split(',')
        .map(id => id.trim())
        .filter(id => id.length);

      if (blockIds?.length) {
        params.blockIds = blockIds;
      }

      if (elementIds?.length) {
        params.elementIds = elementIds;
      }

      return { params };
    }
  } catch (err) {
    console.error(err);
  }

  return null;
}