import * as z from 'zod';
import { renamePrompt } from '~~/prompts';
import { generateText, type UserContent } from "ai";
import { nanoid } from "nanoid";
import { resolveFileUrl } from "~~/utils/url";
import { generateFileToken } from "~~/server/utils/file-token";
import { GatewayFetchError, getProviderDetails, type ModelGateway } from '~~/server/utils/ai-provider';
import { addPendingRename, completeRename } from "~~/server/utils/renames";
import { userEvents } from '~~/server/utils/events';
import { db } from '~~/server/lib/db';
import { type Model } from '~/composables/useModels';
import { topics } from '~~/drizzle/schema';
import { and, eq, gt, isNull, lte, or } from "drizzle-orm";

export default defineEventHandler(async (event) => {
    await protectRoute(event);

    const userId = event.context.user!.id;
    const topicId = getRouterParam(event, 'topicId')!;

    const result = await readValidatedBody(event, (body) =>
        z
            .object({
                modelId: z.string(),
                providerApiKey: z.string().optional(),
            })
            .safeParse(body),
    );
    if (!result.success) {
        throw createError({
            statusCode: 400,
            message: result.error.issues[0]!.message,
            data: {
                code: 'INVALID_BODY',
                ok: false,
            }
        });
    }

    const firstMessage = await db.query.messages.findFirst({
        where: {
            topicId,
            userId,
        },
        orderBy: {
            createdAt: 'asc',
        },
        with: {
            parts: true,
            attachments: {
                with: {
                    file: true,
                }
            },
        },
    });

    if (firstMessage === undefined) {
        throw createError({
            statusCode: 400,
            statusMessage: 'Invalid topic',
            data: {
                code: 'INVALID_TOPIC',
                ok: false,
            }
        });
    }

    if (firstMessage.role !== 'user') {
        throw createError({
            statusCode: 400,
            statusMessage: 'Unimplemented',
            data: {
                code: 'INVALID_TOPIC',
                ok: false,
            }
        });
    }

    const { modelId, providerApiKey } = result.data;

    const topic = await db.query.topics.findFirst({
        where: {
            id: topicId,
            userId,
        },
    });

    if (topic === undefined || topic.userId !== userId) {
        throw createError({
            statusCode: 400,
            statusMessage: 'Invalid topic',
            data: {
                code: 'INVALID_TOPIC',
                ok: false,
            }
        });
    }

    if (topic.renaming && topic.renameExpiresAt && topic.renameExpiresAt > new Date()) {
        throw createError({
            statusCode: 400,
            statusMessage: 'Already renaming',
            data: {
                code: 'ALREADY_RENAMING',
                ok: false,
            }
        });
    }

    const model = await db.query.models.findFirst({
        where: {
            id: modelId,
            userId,
        },
        with: {
            provider: true,
        },
    });

    if (model === undefined || model.userId !== userId) {
        throw createError({
            statusCode: 400,
            statusMessage: 'Invalid model',
            data: {
                code: 'INVALID_MODEL',
                ok: false,
            }
        });
    }

    const providerDetails = await getProviderDetails(model.provider, providerApiKey, model);
    if (!providerDetails.ok) {
        switch (providerDetails.error) {
            case GatewayFetchError.NoProviderApiKey: {
                setResponseStatus(event, 400, "No provider API key");
                throw createError({
                    statusCode: 400,
                    statusMessage: `${model.provider.type} provider requires an API key`,
                    data: {
                        code: 'NO_PROVIDER_API_KEY',
                        ok: false,
                    }
                });
            }
            case GatewayFetchError.NoProviderBaseUrl: {
                throw createError({
                    statusCode: 400,
                    statusMessage: 'Invalid provider URL',
                    data: {
                        code: 'BAD_PROVIDER_URL',
                        ok: false,
                    }
                });
            }
        }
    }

    const { gateway } = providerDetails.data;
    if (gateway === null) {
        throw createError({
            statusCode: 500,
            statusMessage: 'Invalid gateway',
            data: {
                code: 'INVALID_GATEWAY',
                ok: false,
            }
        });
    }

    const content: UserContent = [{
        type: "text",
        text: [firstMessage.content || "Describe the attached content.",
            ...firstMessage.attachments.map(({ file }) => `Attachment: ${file.name}`),
        ].join("\n").slice(0, 12000),
    }];
    if (model.inputModalities.includes("image")) {
        const images = firstMessage.attachments.filter(({ file }) =>
            file.mimeType.startsWith("image/") && file.size <= 10 * 1024 * 1024,
        ).slice(0, 2);
        for (const { file } of images) {
            const url = new URL(resolveFileUrl(file.url));
            if (file.url.startsWith("/api/files/")) {
                const secret = process.env.BETTER_AUTH_SECRET;
                if (!secret) {
                    continue;
                }
                const { exp, sig } = generateFileToken(file.url.slice("/api/files/".length), secret);
                url.searchParams.set("exp", String(exp));
                url.searchParams.set("sig", sig);
            }
            content.push({ type: "image", image: url, mediaType: file.mimeType });
        }
    }

    const attemptId = nanoid();
    const claimed = await db.update(topics).set({
        renaming: true,
        renameAttemptId: attemptId,
        renameExpiresAt: new Date(Date.now() + 90000),
    }).where(and(
        eq(topics.id, topicId),
        eq(topics.userId, userId),
        eq(topics.name, topic.name),
        or(eq(topics.renaming, false), isNull(topics.renameExpiresAt), lte(topics.renameExpiresAt, new Date())),
    )).returning({ id: topics.id });
    if (claimed.length === 0) {
        return { ok: false as const, code: "ALREADY_RENAMING" };
    }
    userEvents.emit(userId, "topics", {
        op: "update", payload: { topicId, renaming: true },
    });
    const abortController = addPendingRename(topicId, attemptId);
    event.waitUntil(autoRename(topicId, attemptId, abortController, { gateway: gateway.gateway, model }, gateway.textTransformer, content, userId));

    return {
        ok: true as const,
    };
});

const autoRename = async (
    topicId: string,
    attemptId: string,
    abortController: AbortController,
    model: {
        gateway: ModelGateway,
        model: Model,
    },
    textTransformer: ((text: string) => string) | ((text: string) => string)[] | undefined,
    content: UserContent,
    userId: string,
) => {
    const deadline = setTimeout(() => abortController.abort(), 90000);
    try {
        const response = await generateText({
            model: model.gateway(model.model.externalId),
            providerOptions: {
                openrouter: {
                    user: userId,
                }
            },
            system: renamePrompt,
            messages: [{ role: "user", content }],
            maxRetries: 0,
            timeout: 90 * 1000,
            abortSignal: abortController.signal,
        });

        let text = response.text;

        if (textTransformer !== undefined) {
            if (Array.isArray(textTransformer)) {
                for (const transformer of textTransformer) {
                    text = transformer(text);
                }
            } else {
                text = textTransformer(text);
            }
        }

        text = text.trim().replace(/^['"]|['"]$/g, "").split("\n")[0]?.trim().slice(0, 120) || "";
        if (!text || abortController.signal.aborted) {
            return;
        }
        const updated = await db.update(topics).set({
            renaming: false,
            renameAttemptId: null,
            renameExpiresAt: null,
            titleSource: "generated",
            name: text,
        }).where(and(
            eq(topics.id, topicId),
            eq(topics.renameAttemptId, attemptId),
            gt(topics.renameExpiresAt, new Date()),
        )).returning({ id: topics.id });
        if (updated.length === 0) {
            return;
        }
        userEvents.emit(model.model.userId, 'topics', {
            op: 'update',
            payload: {
                topicId,
                name: text,
                titleSource: "generated",
                renaming: false,
            },
        });
        topicEvents.emit(topicId, {
            type: 'topic_updated',
            payload: {
                topicId,
                name: text,
                titleSource: "generated",
                renaming: false,
            },
        });
    } catch (error) {
        if (!abortController.signal.aborted) {
            console.error("Failed to auto-rename:", error);
        }
    } finally {
        clearTimeout(deadline);
        completeRename(topicId, attemptId);
        const cleared = await db.update(topics).set({
            renaming: false,
            renameAttemptId: null,
            renameExpiresAt: null,
        }).where(and(eq(topics.id, topicId), eq(topics.renameAttemptId, attemptId))).returning({ id: topics.id });
        if (cleared.length > 0) {
            const payload = { topicId, renaming: false };
            userEvents.emit(userId, "topics", { op: "update", payload });
            topicEvents.emit(topicId, { type: "topic_updated", payload });
        }
    }
}