import DoiClientContract from '#app/Library/Doi/DoiClientContract';
import DoiClientException from '#app/exceptions/DoiClientException';
import { StatusCodes } from 'http-status-codes';
import logger from '@adonisjs/core/services/logger';
import { AxiosResponse } from 'axios';
import { default as axios } from 'axios';

export class DoiClient implements DoiClientContract {
    public username: string;
    public password: string;
    public serviceUrl: string;
    public apiUrl: string;

    constructor() {
        // const datacite_environment = process.env.DATACITE_ENVIRONMENT || 'debug';
        this.username = process.env.DATACITE_USERNAME || '';
        this.password = process.env.DATACITE_PASSWORD || '';
        this.serviceUrl = process.env.DATACITE_SERVICE_URL || '';
        this.apiUrl = process.env.DATACITE_API_URL || 'https://api.datacite.org';

        if (this.username === '' || this.password === '' || this.serviceUrl === '') {
            const message = 'issing configuration settings to properly initialize DOI client';
            logger.error(message);
            throw new DoiClientException(StatusCodes.BAD_REQUEST, message);
        }
    }

    /**
     * Creates a DOI with the given identifier
     *
     * @param doiValue The desired DOI identifier e.g. '10.5072/tethys.999',
     * @param xmlMeta
     * @param landingPageUrl e.g. https://www.tethys.at/dataset/1
     *
     * @return Promise<AxiosResponse<any>> The http response in the form of a axios response
     */
    public async registerDoi(doiValue: string, xmlMeta: string, landingPageUrl: string): Promise<AxiosResponse<any>> {
        //step 1: register metadata via xml upload
        // state draft
        // let response;
        // let url = `${this.serviceUrl}/metadata/${doiValue}`; //https://mds.test.datacite.org/metadata/10.21388/tethys.213
        const auth = {
            username: this.username,
            password: this.password,
        };
        let headers = {
            'Content-Type': 'application/xml;charset=UTF-8',
        };
        try {
            const metadataResponse = await axios.put(`${this.serviceUrl}/metadata/${doiValue}`, xmlMeta, { auth, headers });

            // Response Codes
            // 201 Created: operation successful
            // 401 Unauthorised: no login
            // 403 Forbidden: login problem, quota exceeded
            // 415 Wrong Content Type : Not including content type in the header.
            // 422 Unprocessable Entity : invalid XML
            // let test = metadataResponse.data; // 'OK (10.21388/TETHYS.213)'
            if (metadataResponse.status !== 201) {
                const message = `Unexpected DataCite MDS response code ${metadataResponse.status}`;
                logger.error(message);
                throw new DoiClientException(metadataResponse.status, message);
            }

            const doiResponse = await axios.put(`${this.serviceUrl}/doi/${doiValue}`, `doi=${doiValue}\nurl=${landingPageUrl}`, {
                auth,
                headers,
            });

            // Response Codes
            // 201 Created: operation successful
            // 400 Bad Request: request body must be exactly two lines: DOI and URL; wrong domain, wrong prefix;
            // 401 Unauthorised: no login
            // 403 Forbidden: login problem, quota exceeded
            // 412 Precondition failed: metadata must be uploaded first.
            if (doiResponse.status !== 201) {
                const message = `Unexpected DataCite MDS response code ${doiResponse.status}`;
                logger.error(message);
                throw new DoiClientException(doiResponse.status, message);
            }

            return doiResponse;
        } catch (error) {
            // const message = `request for registering DOI failed with ${error.message}`;
            // Handle the error, log it, or rethrow as needed
            logger.error(error.message);
            throw new DoiClientException(error.response.status, error.response.data);
        }
    }

    /**
     * Retrieves DOI information from DataCite REST API
     *
     * @param doiValue The DOI identifier e.g. '10.5072/tethys.999'
     * @returns Promise with DOI information or null if not found
     */
    public async getDoiInfo(doiValue: string): Promise<any | null> {
        try {
            // Use configurable DataCite REST API URL
            const dataciteApiUrl = `${this.apiUrl}/dois/${doiValue}`;
            const response = await axios.get(dataciteApiUrl, {
                headers: {
                    Accept: 'application/vnd.api+json',
                },
            });

            if (response.status === 200 && response.data.data) {
                return {
                    created: response.data.data.attributes.created,
                    registered: response.data.data.attributes.registered,
                    updated: response.data.data.attributes.updated,
                    published: response.data.data.attributes.published,
                    state: response.data.data.attributes.state,
                    url: response.data.data.attributes.url,
                    metadata: response.data.data.attributes,
                };
            }
        } catch (error) {
            if (error.response?.status === 404) {
                logger.debug(`DOI ${doiValue} not found in DataCite`);
                return null;
            }

            logger.debug(`DataCite REST API failed for ${doiValue}: ${error.message}`);

            // Fallback to MDS API
            return await this.getDoiInfoFromMds(doiValue);
        }

        return null;
    }

    /**
     * Fallback method to get DOI info from MDS API
     *
     * @param doiValue The DOI identifier
     * @returns Promise with basic DOI information or null
     */
    private async getDoiInfoFromMds(doiValue: string): Promise<any | null> {
        try {
            const auth = {
                username: this.username,
                password: this.password,
            };

            // Get DOI URL
            const doiResponse = await axios.get(`${this.serviceUrl}/doi/${doiValue}`, { auth });

            if (doiResponse.status === 200) {
                // Get metadata if available
                try {
                    const metadataResponse = await axios.get(`${this.serviceUrl}/metadata/${doiValue}`, {
                        auth,
                        headers: {
                            Accept: 'application/xml',
                        },
                    });

                    return {
                        url: doiResponse.data.trim(),
                        metadata: metadataResponse.data,
                        created: new Date().toISOString(), // MDS doesn't provide creation dates
                        registered: new Date().toISOString(), // Use current time as fallback
                        source: 'mds',
                    };
                } catch (metadataError) {
                    // Return basic info even if metadata fetch fails
                    return {
                        url: doiResponse.data.trim(),
                        created: new Date().toISOString(),
                        registered: new Date().toISOString(),
                        source: 'mds',
                    };
                }
            }
        } catch (error) {
            if (error.response?.status === 404) {
                logger.debug(`DOI ${doiValue} not found in DataCite MDS`);
                return null;
            }

            logger.debug(`DataCite MDS API failed for ${doiValue}: ${error.message}`);
        }

        return null;
    }

    /**
     * Checks if a DOI exists in DataCite
     *
     * @param doiValue The DOI identifier
     * @returns Promise<boolean> True if DOI exists
     */
    public async doiExists(doiValue: string): Promise<boolean> {
        const doiInfo = await this.getDoiInfo(doiValue);
        return doiInfo !== null;
    }

    /**
     * Gets the last modification date of a DOI
     *
     * @param doiValue The DOI identifier
     * @returns Promise<Date | null> Last modification date or creation date if never updated, null if not found
     */
    public async getDoiLastModified(doiValue: string): Promise<Date | null> {
        const doiInfo = await this.getDoiInfo(doiValue);

        if (doiInfo) {
            // Use updated date if available, otherwise fall back to created/registered date
            const dateToUse = doiInfo.updated || doiInfo.registered || doiInfo.created;

            if (dateToUse) {
                logger.debug(
                    `DOI ${doiValue}: Using ${doiInfo.updated ? 'updated' : doiInfo.registered ? 'registered' : 'created'} date: ${dateToUse}`,
                );
                return new Date(dateToUse);
            }
        }

        return null;
    }

    /**
     * Makes a DOI unfindable (registered but not discoverable)
     * Note: DOIs cannot be deleted, only made unfindable
     * await doiClient.makeDoiUnfindable('10.21388/tethys.231');
     *
     * @param doiValue The DOI identifier e.g. '10.5072/tethys.999'
     * @returns Promise<AxiosResponse<any>> The http response
     */
    public async makeDoiUnfindable(doiValue: string): Promise<AxiosResponse<any>> {
        const auth = {
            username: this.username,
            password: this.password,
        };

        try {
            // First, check if DOI exists
            const exists = await this.doiExists(doiValue);
            if (!exists) {
                throw new DoiClientException(404, `DOI ${doiValue} not found`);
            }

            // Delete the DOI URL mapping to make it unfindable
            // This removes the URL but keeps the metadata registered
            const response = await axios.delete(`${this.serviceUrl}/doi/${doiValue}`, { auth });

            // Response Codes for DELETE /doi/{doi}
            // 200 OK: operation successful
            // 401 Unauthorized: no login
            // 403 Forbidden: login problem, quota exceeded
            // 404 Not Found: DOI does not exist
            if (response.status !== 200) {
                const message = `Unexpected DataCite MDS response code ${response.status}`;
                logger.error(message);
                throw new DoiClientException(response.status, message);
            }

            logger.info(`DOI ${doiValue} successfully made unfindable`);
            return response;
        } catch (error) {
            logger.error(`Failed to make DOI ${doiValue} unfindable: ${error.message}`);
            if (error instanceof DoiClientException) {
                throw error;
            }
            throw new DoiClientException(error.response?.status || 500, error.response?.data || error.message);
        }
    }

    /**
     * Makes a DOI findable again by re-registering the URL
     * await doiClient.makeDoiFindable(
     *     '10.21388/tethys.231',
     *     'https://doi.dev.tethys.at/10.21388/tethys.231'
     * );
     *
     * @param doiValue The DOI identifier e.g. '10.5072/tethys.999'
     * @param landingPageUrl The landing page URL
     * @returns Promise<AxiosResponse<any>> The http response
     */
    public async makeDoiFindable(doiValue: string, landingPageUrl: string): Promise<AxiosResponse<any>> {
        const auth = {
            username: this.username,
            password: this.password,
        };

        try {
            // Re-register the DOI with its URL to make it findable again
            const response = await axios.put(`${this.serviceUrl}/doi/${doiValue}`, `doi=${doiValue}\nurl=${landingPageUrl}`, { auth });

            // Response Codes for PUT /doi/{doi}
            // 201 Created: operation successful
            // 400 Bad Request: request body must be exactly two lines: DOI and URL
            // 401 Unauthorized: no login
            // 403 Forbidden: login problem, quota exceeded
            // 412 Precondition failed: metadata must be uploaded first
            if (response.status !== 201) {
                const message = `Unexpected DataCite MDS response code ${response.status}`;
                logger.error(message);
                throw new DoiClientException(response.status, message);
            }

            logger.info(`DOI ${doiValue} successfully made findable again`);
            return response;
        } catch (error) {
            logger.error(`Failed to make DOI ${doiValue} findable: ${error.message}`);
            if (error instanceof DoiClientException) {
                throw error;
            }
            throw new DoiClientException(error.response?.status || 500, error.response?.data || error.message);
        }
    }

    /**
     * Gets the current state of a DOI (draft, registered, findable)
     * const state = await doiClient.getDoiState('10.21388/tethys.231');
     * console.log(`Current state: ${state}`); // 'findable'
     *
     * @param doiValue The DOI identifier
     * @returns Promise<string | null> The DOI state or null if not found
     */
    public async getDoiState(doiValue: string): Promise<string | null> {
        const doiInfo = await this.getDoiInfo(doiValue);
        return doiInfo?.state || null;
    }
}