import { LightningElement, api } from 'lwc';
import { ShowToastEvent } from 'lightning/platformShowToastEvent';
import getDocGenPreview from '@salesforce/apex/CLMAdminService.getDocGenPreview';
import listAccountSettings from '@salesforce/apex/CLMAdminService.listAccountSettings';
import listLetterSettings from '@salesforce/apex/CLMAdminService.listLetterSettings';

export default class ClmRequestPreview extends LightningElement {
    @api recordId;
    @api objectApiName;

    accountCode = '';
    letterCode = '';
    accountOptions = [];
    letterOptions = [];
    preview;
    isBusy = false;
    message = '';
    messageVariant = 'info';

    connectedCallback() {
        this.initialize();
    }

    get hasPreview() {
        return Boolean(this.preview);
    }

    get resultClass() {
        return `result result-${this.messageVariant}`;
    }

    async initialize(forceReload = false) {
        if (!this.recordId) {
            return;
        }

        this.isBusy = true;
        this.clearMessage();

        try {
            const accounts = await listAccountSettings();
            this.accountOptions = (accounts || []).map((account) => ({
                label: account.accountDisplayName,
                value: account.accountCode
            }));

            if ((!this.accountCode || forceReload) && this.accountOptions.length > 0) {
                this.accountCode = this.accountOptions[0].value;
            }

            await this.loadLetterOptions(forceReload);
            await this.loadPreview();
        } catch (error) {
            this.handleError(error, 'Unable to initialize CLM preview');
        } finally {
            this.isBusy = false;
        }
    }

    async loadLetterOptions(forceReload) {
        const letters = await listLetterSettings({ accountCode: this.accountCode });
        this.letterOptions = (letters || []).map((letter) => ({
            label: letter.letterDisplayName,
            value: letter.letterCode
        }));

        const hasExistingSelection = this.letterOptions.some((letter) => letter.value === this.letterCode);
        if (!hasExistingSelection || forceReload || !this.letterCode) {
            const defaultLetter = (letters || []).find((letter) => letter.isDefault);
            this.letterCode = defaultLetter
                ? defaultLetter.letterCode
                : this.letterOptions.length > 0
                    ? this.letterOptions[0].value
                    : '';
        }
    }

    async loadPreview() {
        if (!this.recordId) {
            this.showMessage('No record context — place this component on a record page.', 'warning');
            return;
        }
        this.preview = await getDocGenPreview({
            appraiserCaseId: this.recordId,
            accountCode: this.accountCode,
            letterCode: this.letterCode
        });
        this.showMessage('Preview loaded.', 'success');
    }

    async handleAccountChange(event) {
        this.accountCode = event.detail.value;
        await this.refreshAll(true);
    }

    async handleLetterChange(event) {
        this.letterCode = event.detail.value;
        await this.refreshAll(false);
    }

    async refreshAll(forceReloadLetters) {
        this.isBusy = true;
        this.clearMessage();

        try {
            if (forceReloadLetters) {
                await this.loadLetterOptions(true);
            }
            await this.loadPreview();
        } catch (error) {
            this.handleError(error, 'Unable to refresh CLM preview');
        } finally {
            this.isBusy = false;
        }
    }

    clearMessage() {
        this.message = '';
        this.messageVariant = 'info';
    }

    showMessage(message, variant) {
        this.message = message;
        this.messageVariant = variant;
    }

    handleError(error, title) {
        const bodyMessage = error && error.body ? error.body.message : null;
        const directMessage = error ? error.message : null;
        const message = bodyMessage || directMessage || 'Unknown error';

        this.showMessage(message, 'error');
        this.dispatchEvent(
            new ShowToastEvent({
                title,
                message,
                variant: 'error'
            })
        );
    }
}