import {
  and,
  asc,
  desc,
  eq,
  ilike,
  isNotNull,
  lte,
  or,
  sql,
  type SQL,
} from "drizzle-orm";
import type { Db } from "@paperclipai/db";
import {
  approvals,
  decisionTrainingExamples,
  executionWorkspaces,
  heartbeatRuns,
  issueApprovals,
  issueComments,
  issueExecutionDecisions,
  issues,
  issueThreadInteractions,
  projectWorkspaces,
} from "@paperclipai/db";
import type {
  DecisionTrainingNotesHistoryEntry,
  DecisionTrainingSnapshotV1,
  DecisionTrainingSourceKind,
} from "@paperclipai/shared";
import { DECISION_TRAINING_RETENTION_POLICY } from "@paperclipai/shared";
import { conflict, notFound } from "../errors.js";

type CaptureInput = {
  companyId: string;
  sourceKind: DecisionTrainingSourceKind;
  sourceId: string;
  issueId: string;
};

type SourceDecision = {
  cutoffAt: Date;
  outcome: string | null;
  payload: Record<string, unknown>;
  actor: Record<string, unknown> | null;
  exactRunId: string | null;
};

type ListInput = {
  readCondition?: SQL<boolean>;
  projectId?: string;
  kind?: DecisionTrainingSourceKind;
  author?: string;
  q?: string;
};

type ScrubDeletedCommentsInput = {
  companyId: string;
  issueId: string;
  commentIds: string[];
  deletedAt: Date;
};

function jsonCopy(value: unknown): Record<string, unknown> {
  return JSON.parse(JSON.stringify(value)) as Record<string, unknown>;
}

function findCommitSha(value: unknown): string | null {
  if (!value || typeof value !== "object") return null;
  if (Array.isArray(value)) {
    for (const item of value) {
      const found = findCommitSha(item);
      if (found) return found;
    }
    return null;
  }
  const record = value as Record<string, unknown>;
  for (const key of ["commitSha", "commitSHA", "gitCommitSha", "headSha", "commit"]) {
    const candidate = record[key];
    if (typeof candidate === "string" && /^[0-9a-f]{7,64}$/i.test(candidate)) return candidate;
  }
  for (const nested of Object.values(record)) {
    const found = findCommitSha(nested);
    if (found) return found;
  }
  return null;
}

async function loadSourceDecision(db: Db, input: CaptureInput, capturedAt: Date): Promise<SourceDecision> {
  if (input.sourceKind === "interaction") {
    const row = await db.query.issueThreadInteractions.findFirst({
      where: and(
        eq(issueThreadInteractions.id, input.sourceId),
        eq(issueThreadInteractions.companyId, input.companyId),
        eq(issueThreadInteractions.issueId, input.issueId),
      ),
    });
    if (!row) throw notFound("Decision interaction not found");
    const resolved = row.resolvedAt != null && row.status !== "pending";
    return {
      cutoffAt: resolved ? row.resolvedAt! : capturedAt,
      outcome: resolved ? row.status : null,
      payload: jsonCopy({
        kind: row.kind,
        title: row.title,
        summary: row.summary,
        payload: row.payload,
        result: resolved ? row.result : null,
      }),
      actor: jsonCopy(resolved
        ? { userId: row.resolvedByUserId, agentId: row.resolvedByAgentId }
        : { userId: row.createdByUserId, agentId: row.createdByAgentId }),
      exactRunId: row.sourceRunId,
    };
  }

  if (input.sourceKind === "approval") {
    const rows = await db
      .select({ approval: approvals })
      .from(approvals)
      .innerJoin(issueApprovals, and(
        eq(issueApprovals.approvalId, approvals.id),
        eq(issueApprovals.issueId, input.issueId),
        eq(issueApprovals.companyId, input.companyId),
      ))
      .where(and(eq(approvals.id, input.sourceId), eq(approvals.companyId, input.companyId)))
      .limit(1);
    const row = rows[0]?.approval;
    if (!row) throw notFound("Decision approval not found");
    const resolved = row.decidedAt != null && row.status !== "pending";
    return {
      cutoffAt: resolved ? row.decidedAt! : capturedAt,
      outcome: resolved ? row.status : null,
      payload: jsonCopy({ type: row.type, payload: row.payload, decisionNote: resolved ? row.decisionNote : null }),
      actor: jsonCopy(resolved
        ? { userId: row.decidedByUserId }
        : { userId: row.requestedByUserId, agentId: row.requestedByAgentId }),
      exactRunId: null,
    };
  }

  const row = await db.query.issueExecutionDecisions.findFirst({
    where: and(
      eq(issueExecutionDecisions.id, input.sourceId),
      eq(issueExecutionDecisions.companyId, input.companyId),
      eq(issueExecutionDecisions.issueId, input.issueId),
    ),
  });
  if (!row) throw notFound("Execution decision not found");
  return {
    cutoffAt: row.createdAt,
    outcome: row.outcome,
    payload: jsonCopy({ stageId: row.stageId, stageType: row.stageType, body: row.body }),
    actor: jsonCopy({ userId: row.actorUserId, agentId: row.actorAgentId }),
    exactRunId: row.createdByRunId,
  };
}

export async function captureDecisionSnapshot(
  db: Db,
  input: CaptureInput,
  capturedAt = new Date(),
): Promise<{ cutoffAt: Date; decisionOutcome: string | null; snapshot: DecisionTrainingSnapshotV1 }> {
  const issue = await db.query.issues.findFirst({
    where: and(eq(issues.id, input.issueId), eq(issues.companyId, input.companyId)),
  });
  if (!issue) throw notFound("Issue not found");

  const decision = await loadSourceDecision(db, input, capturedAt);
  const comments = await db
    .select()
    .from(issueComments)
    .where(and(
      eq(issueComments.companyId, input.companyId),
      eq(issueComments.issueId, input.issueId),
      lte(issueComments.createdAt, decision.cutoffAt),
    ))
    .orderBy(asc(issueComments.createdAt), asc(issueComments.id));
  const runs = await db
    .select()
    .from(heartbeatRuns)
    .where(and(
      eq(heartbeatRuns.companyId, input.companyId),
      isNotNull(heartbeatRuns.startedAt),
      lte(heartbeatRuns.startedAt, decision.cutoffAt),
      lte(heartbeatRuns.updatedAt, decision.cutoffAt),
      or(
        sql`${heartbeatRuns.contextSnapshot} ->> 'issueId' = ${input.issueId}`,
        sql`${heartbeatRuns.contextSnapshot} ->> 'taskId' = ${input.issueId}`,
      ),
    ))
    .orderBy(asc(heartbeatRuns.startedAt), asc(heartbeatRuns.id));

  const [projectWorkspace] = issue.projectId
    ? await db
      .select()
      .from(projectWorkspaces)
      .where(and(
        eq(projectWorkspaces.companyId, input.companyId),
        eq(projectWorkspaces.projectId, issue.projectId),
        lte(projectWorkspaces.createdAt, decision.cutoffAt),
        lte(projectWorkspaces.updatedAt, decision.cutoffAt),
      ))
      .orderBy(desc(projectWorkspaces.isPrimary), desc(projectWorkspaces.updatedAt))
      .limit(1)
    : [];
  const [executionWorkspace] = await db
    .select()
    .from(executionWorkspaces)
    .where(and(
      eq(executionWorkspaces.companyId, input.companyId),
      eq(executionWorkspaces.sourceIssueId, input.issueId),
      lte(executionWorkspaces.openedAt, decision.cutoffAt),
      lte(executionWorkspaces.lastUsedAt, decision.cutoffAt),
      lte(executionWorkspaces.updatedAt, decision.cutoffAt),
    ))
    .orderBy(desc(executionWorkspaces.lastUsedAt), desc(executionWorkspaces.id))
    .limit(1);

  const exactRun = decision.exactRunId ? runs.find((run) => run.id === decision.exactRunId) ?? null : null;
  const latestRunWithCommit = [...runs].reverse().find((run) => findCommitSha(run.contextSnapshot)) ?? null;
  const exactCommit = exactRun ? findCommitSha(exactRun.contextSnapshot) : null;
  const nearestCommit = latestRunWithCommit ? findCommitSha(latestRunWithCommit.contextSnapshot) : null;
  const workspaceCommit = findCommitSha(executionWorkspace?.metadata) ?? findCommitSha(projectWorkspace?.metadata);
  const commitSha = exactCommit ?? nearestCommit ?? workspaceCommit;

  return {
    cutoffAt: decision.cutoffAt,
    decisionOutcome: decision.outcome,
    snapshot: {
      version: 1,
      retention: {
        policy: DECISION_TRAINING_RETENTION_POLICY,
        commentDeletion: "redact",
        issueDeletion: "cascade",
      },
      capturedAt: capturedAt.toISOString(),
      cutoff: {
        at: decision.cutoffAt.toISOString(),
        lastCommentId: comments.at(-1)?.id ?? null,
        commentCount: comments.length,
      },
      issue: jsonCopy(issue),
      comments: comments.map(jsonCopy),
      runs: runs.map(jsonCopy),
      decision: {
        kind: input.sourceKind,
        payload: decision.payload,
        actor: decision.actor,
        outcome: decision.outcome,
      },
      code: {
        repoUrl: executionWorkspace?.repoUrl ?? projectWorkspace?.repoUrl ?? null,
        ref: executionWorkspace?.branchName
          ?? executionWorkspace?.baseRef
          ?? projectWorkspace?.repoRef
          ?? projectWorkspace?.defaultRef
          ?? null,
        commitSha: commitSha ?? null,
        resolution: exactCommit
          ? "exact"
          : nearestCommit
            ? "nearest_run"
            : workspaceCommit
              ? "workspace"
              : "none",
      },
    },
  };
}

export function decisionTrainingService(db: Db) {
  return {
    // Capture the snapshot the way create() would, but without persisting it, so
    // the drawer's create state can preview exactly what will be frozen before
    // the user commits.
    preview: async (input: CaptureInput) => captureDecisionSnapshot(db, input),
    create: async (input: CaptureInput & { notes: string; createdByUserId: string }) => {
      const captured = await captureDecisionSnapshot(db, input);
      const rows = await db
        .insert(decisionTrainingExamples)
        .values({
          companyId: input.companyId,
          sourceKind: input.sourceKind,
          sourceId: input.sourceId,
          issueId: input.issueId,
          cutoffAt: captured.cutoffAt,
          notes: input.notes,
          notesHistory: [],
          decisionOutcome: captured.decisionOutcome,
          retentionPolicy: DECISION_TRAINING_RETENTION_POLICY,
          snapshot: captured.snapshot,
          createdByUserId: input.createdByUserId,
        })
        .onConflictDoNothing({
          target: [
            decisionTrainingExamples.sourceKind,
            decisionTrainingExamples.sourceId,
            decisionTrainingExamples.createdByUserId,
          ],
        })
        .returning();
      if (!rows[0]) throw conflict("This decision is already trained by this user");
      return rows[0];
    },
    list: async (companyId: string, input: ListInput = {}) => {
      const filters: SQL[] = [eq(decisionTrainingExamples.companyId, companyId)];
      if (input.readCondition) filters.push(input.readCondition);
      if (input.projectId) filters.push(eq(issues.projectId, input.projectId));
      if (input.kind) filters.push(eq(decisionTrainingExamples.sourceKind, input.kind));
      if (input.author) filters.push(eq(decisionTrainingExamples.createdByUserId, input.author));
      if (input.q) {
        const query = `%${input.q}%`;
        filters.push(or(
          ilike(decisionTrainingExamples.notes, query),
          ilike(issues.title, query),
          ilike(issues.identifier, query),
        )!);
      }
      return db
        .select({ example: decisionTrainingExamples, issueTitle: issues.title, issueIdentifier: issues.identifier })
        .from(decisionTrainingExamples)
        .innerJoin(issues, eq(decisionTrainingExamples.issueId, issues.id))
        .where(and(...filters))
        .orderBy(desc(decisionTrainingExamples.createdAt), desc(decisionTrainingExamples.id));
    },
    getById: async (id: string) => db.query.decisionTrainingExamples.findFirst({
      where: eq(decisionTrainingExamples.id, id),
    }),
    updateNotes: async (id: string, author: string, notes: string) => db.transaction(async (tx) => {
      const row = await tx.query.decisionTrainingExamples.findFirst({
        where: eq(decisionTrainingExamples.id, id),
      });
      if (!row) return null;
      if (notes === row.notes) return row;
      const history: DecisionTrainingNotesHistoryEntry[] = [
        ...(row.notesHistory ?? []),
        { author, at: new Date().toISOString(), body: row.notes },
      ];
      const [updated] = await tx
        .update(decisionTrainingExamples)
        .set({ notes, notesHistory: history, updatedAt: new Date() })
        .where(eq(decisionTrainingExamples.id, id))
        .returning();
      return updated ?? null;
    }),
    scrubDeletedComments: async (
      input: ScrubDeletedCommentsInput,
      dbOrTx: any = db,
    ) => {
      if (input.commentIds.length === 0) return { updatedCount: 0 };
      const commentIds = new Set(input.commentIds);
      const rows = await dbOrTx
        .select({ id: decisionTrainingExamples.id, snapshot: decisionTrainingExamples.snapshot })
        .from(decisionTrainingExamples)
        .where(and(
          eq(decisionTrainingExamples.companyId, input.companyId),
          eq(decisionTrainingExamples.issueId, input.issueId),
        ));
      let updatedCount = 0;
      for (const row of rows) {
        let changed = false;
        const comments = row.snapshot.comments.map((comment: Record<string, unknown>) => {
          if (typeof comment.id !== "string" || !commentIds.has(comment.id)) return comment;
          changed = true;
          return {
            id: comment.id,
            issueId: input.issueId,
            body: "",
            presentation: null,
            metadata: null,
            deletedAt: input.deletedAt.toISOString(),
            retentionRedaction: {
              reason: "source_comment_deleted",
              policy: DECISION_TRAINING_RETENTION_POLICY,
            },
          };
        });
        if (!changed) continue;
        await dbOrTx
          .update(decisionTrainingExamples)
          .set({
            retentionPolicy: DECISION_TRAINING_RETENTION_POLICY,
            snapshot: {
              ...row.snapshot,
              retention: {
                policy: DECISION_TRAINING_RETENTION_POLICY,
                commentDeletion: "redact",
                issueDeletion: "cascade",
              },
              comments,
            },
            updatedAt: input.deletedAt,
          })
          .where(eq(decisionTrainingExamples.id, row.id));
        updatedCount += 1;
      }
      return { updatedCount };
    },
    delete: async (id: string) => db
      .delete(decisionTrainingExamples)
      .where(eq(decisionTrainingExamples.id, id))
      .returning({ id: decisionTrainingExamples.id }),
  };
}