import type { Author } from "@bindings/cob/Author";
import type { CreateReviewArgs } from "@bindings/cob/patch/CreateReviewArgs";
import type { Patch } from "@bindings/cob/patch/Patch";
import type { Verdict } from "@bindings/cob/patch/Verdict";
import type { CodeLocation } from "@bindings/cob/thread/CodeLocation";
import type { CodeRange } from "@bindings/cob/thread/CodeRange";
import type { Comment } from "@bindings/cob/thread/Comment";

import { z } from "zod";

import useLocalStorage from "@app/lib/useLocalStorage.svelte";
import { publicKeyFromDid } from "@app/lib/utils";

import { invoke } from "./invoke";

// This is different from the stored draft review to align it with a
// published `Review`.
export interface DraftReview {
  id: string;
  draft: true;
  rid: string;
  author: Author;
  revisionId: string;
  verdict?: Verdict;
  summary?: string;
  labels: string[];
  comments: Array<Comment<CodeLocation>>;
  checkedFiles: string[];
}

const codeRangeSchema: z.Schema<CodeRange> = z.union([
  z.object({
    type: z.literal("lines"),
    range: z.object({ start: z.number(), end: z.number() }),
  }),
  z.object({
    type: z.literal("chars"),
    line: z.number(),
    range: z.object({ start: z.number(), end: z.number() }),
  }),
]);

const draftReviewStoredSchema = z.object({
  id: z.string(),
  rid: z.string(),
  // Node ID of the identity that wrote the draft. Optional so drafts stored
  // before this field existed keep working; those are treated as belonging to
  // whoever is signed in, which is how they behaved previously.
  nid: z.string().optional(),
  // Patch the revision belongs to. Only used to prune drafts whose revision has
  // gone away, which can't be done from the revision id alone. Optional for the
  // same backwards-compatibility reason.
  patchId: z.string().optional(),
  revision: z.string(),
  verdict: z.union([z.literal("accept"), z.literal("reject")]).optional(),
  summary: z.string().default(""),
  labels: z.array(z.string()),
  comments: z.array(
    z.object({
      id: z.string(),
      body: z.string(),
      location: z
        .object({
          commit: z.string(),
          path: z.string(),
          old: codeRangeSchema.nullable(),
          new: codeRangeSchema.nullable(),
        })
        .optional(),
    }),
  ),
  checkedFiles: z.array(z.string()).default([]),
});

type DraftReviewStored = z.infer<typeof draftReviewStoredSchema>;

const storage = useLocalStorage(
  "repo.patches.draftReviews",
  z.record(z.string(), draftReviewStoredSchema),
  {},
);

function belongsTo(draft: DraftReviewStored, nid: string): boolean {
  return draft.nid === undefined || draft.nid === nid;
}

export const draftReviewStorage = {
  get(id: string, author: Author): DraftReview | undefined {
    const draftReviewStored = storage.value[id];
    if (
      !draftReviewStored ||
      !belongsTo(draftReviewStored, publicKeyFromDid(author.did))
    ) {
      return undefined;
    }

    return draftReviewFromStored(draftReviewStored, author);
  },

  getForRevision(revisionId: string, author: Author): DraftReview | undefined {
    const nid = publicKeyFromDid(author.did);
    const draftReviewStored = Object.values(storage.value).find(
      draftReview =>
        draftReview.revision === revisionId && belongsTo(draftReview, nid),
    );

    if (draftReviewStored) {
      return draftReviewFromStored(draftReviewStored, author);
    }
  },

  create(
    rid: string,
    patchId: string,
    revisionId: string,
    nid: string,
  ): string {
    const id = crypto.randomUUID();
    storage.update(reviews => {
      reviews[id] = {
        id,
        rid,
        nid,
        patchId,
        revision: revisionId,
        // Written down rather than defaulted when the bar reads the draft, so
        // an absent verdict unambiguously means "comment only".
        verdict: "accept",
        summary: "",
        labels: [],
        comments: [],
        checkedFiles: [],
      };
      return reviews;
    });
    return id;
  },

  isFileChecked(id: string, filePath: string): boolean {
    return storage.value[id]?.checkedFiles?.includes(filePath) ?? false;
  },

  toggleCheckedFile(id: string, filePath: string) {
    updateStoredDraftReview(id, review => {
      const set = new Set(review.checkedFiles);
      if (set.has(filePath)) {
        set.delete(filePath);
      } else {
        set.add(filePath);
      }
      return { ...review, checkedFiles: [...set] };
    });
  },

  hasForRevision(revisionId: string, nid: string): boolean {
    return Object.values(storage.value).some(
      review => review.revision === revisionId && belongsTo(review, nid),
    );
  },

  // Drop drafts whose revision is gone — redacted, or a patch deleted from this
  // node. Drafts predating `patchId` are skipped: there is no way to tell which
  // patch they belong to.
  pruneStale(patchId: string, revisionIds: string[], nid: string) {
    const live = new Set(revisionIds);
    storage.update(reviews => {
      for (const [id, review] of Object.entries(reviews)) {
        if (
          review.patchId === patchId &&
          belongsTo(review, nid) &&
          !live.has(review.revision)
        ) {
          delete reviews[id];
        }
      }
      return reviews;
    });
  },

  update(
    id: string,
    props: { summary: string; verdict: Verdict | undefined; labels: string[] },
  ) {
    updateStoredDraftReview(id, review => {
      return Object.assign(review, props);
    });
  },

  delete(id: string): DraftReviewStored | undefined {
    const review = storage.value[id];
    storage.update(reviews => {
      delete reviews[id];
      return reviews;
    });
    return review;
  },

  deleteComment(id: string, commentId: string) {
    updateStoredDraftReview(id, review => {
      // Guard the miss: `splice(-1, 1)` would drop the last comment instead of
      // doing nothing.
      const index = review.comments.findIndex(
        comment => comment.id === commentId,
      );
      if (index === -1) {
        return review;
      }
      review.comments.splice(index, 1);
      return review;
    });
  },

  addComment(
    id: string,
    comment: {
      body: string;
      location: CodeLocation;
    },
  ): string {
    const commentId = crypto.randomUUID();
    updateStoredDraftReview(id, review => {
      review.comments.push({
        id: commentId,
        body: comment.body,
        location: comment.location,
      });
      return review;
    });
    return commentId;
  },

  updateComment(
    id: string,
    commentId: string,
    comment: {
      body: string;
    },
  ) {
    updateStoredDraftReview(id, review => {
      const storedComment = review.comments.find(
        comment => comment.id === commentId,
      );

      if (!storedComment) {
        throw new Error(
          `Comment ${commentId} does not exist for draft review ${id}`,
        );
      }

      storedComment.body = comment.body;
      return review;
    });
  },

  async publish(id: string) {
    const draftReviewStored = storage.value[id];
    if (!draftReviewStored) {
      throw new Error(
        `Failed to publish draft review: Review ${id} does not exist`,
      );
    }

    // Discard the draft only once the review is on the network. Deleting first
    // loses every comment if the call fails, and leaves the bar unable to
    // retry because the draft it is rendering no longer exists.
    await invoke<Patch>("create_patch_review", {
      args: {
        rid: draftReviewStored.rid,
        revision: draftReviewStored.revision,
        verdict: draftReviewStored.verdict ?? null,
        summary: draftReviewStored.summary,
        labels: draftReviewStored.labels,
        comments: draftReviewStored.comments.map(storedComment => ({
          body: storedComment.body,
          location: storedComment.location ?? null,
        })),
      } satisfies CreateReviewArgs,
    });

    draftReviewStorage.delete(id);
  },
};

function updateStoredDraftReview(
  id: string,
  update: (draftReviewStored: DraftReviewStored) => DraftReviewStored,
): void {
  storage.update(reviews => {
    const review = reviews[id];
    if (!review) {
      throw new Error(`Draft review ${id} does not exist`);
    }

    reviews[id] = update(review);
    return reviews;
  });
}

function draftReviewFromStored(
  draftReviewStored: z.infer<typeof draftReviewStoredSchema>,
  author: Author,
): DraftReview {
  return {
    id: draftReviewStored.id,
    draft: true,
    rid: draftReviewStored.rid,
    summary: draftReviewStored.summary,
    author,
    revisionId: draftReviewStored.revision,
    verdict: draftReviewStored.verdict,
    labels: draftReviewStored.labels,
    checkedFiles: draftReviewStored.checkedFiles,
    comments: draftReviewStored.comments.map(rawComment => ({
      id: rawComment.id,
      author,
      edits: [
        {
          author,
          timestamp: 0,
          body: rawComment.body,
        },
      ],
      reactions: [],
      replyTo: null,
      location: rawComment.location ?? null,
      resolved: false,
    })),
  };
}