import { SourcebotConfig } from "@sourcebot/schemas/v3/index.type";
import { indexSchema } from "@sourcebot/schemas/v3/index.schema";
import { readFile } from 'fs/promises';
import stripJsonComments from 'strip-json-comments';
import { Ajv } from "ajv";

const ajv = new Ajv({
    validateFormats: false,
});

// From https://developer.mozilla.org/en-US/docs/Glossary/Base64#the_unicode_problem
export const base64Decode = (base64: string): string => {
    const binString = atob(base64);
    return Buffer.from(Uint8Array.from(binString, (m) => m.codePointAt(0)!).buffer).toString();
}

export const isRemotePath = (path: string) => {
    return path.startsWith('https://') || path.startsWith('http://');
}

export const loadConfig = async (configPath: string): Promise<SourcebotConfig> => {
    const configContent = await (async () => {
        if (isRemotePath(configPath)) {
            const response = await fetch(configPath);
            if (!response.ok) {
                throw new Error(`Failed to fetch config file ${configPath}: ${response.statusText}`);
            }
            return response.text();
        } else {
            // Retry logic for handling race conditions with mounted volumes
            const maxAttempts = 5;
            const retryDelayMs = 2000;
            let lastError: Error | null = null;

            for (let attempt = 1; attempt <= maxAttempts; attempt++) {
                try {
                    return await readFile(configPath, {
                        encoding: 'utf-8',
                    });
                } catch (error) {
                    lastError = error as Error;
                    
                    // Only retry on ENOENT errors (file not found)
                    if ((error as NodeJS.ErrnoException)?.code !== 'ENOENT') {
                        throw error; // Throw immediately for non-ENOENT errors
                    }
                    
                    // Log warning before retry (except on the last attempt)
                    if (attempt < maxAttempts) {
                        console.warn(`Config file not found, retrying in 2s... (Attempt ${attempt}/${maxAttempts})`);
                        await new Promise(resolve => setTimeout(resolve, retryDelayMs));
                    }
                }
            }
            
            // If we've exhausted all retries, throw the last ENOENT error
            if (lastError) {
                throw lastError;
            }
            
            throw new Error('Failed to load config after all retry attempts');
        }
    })();

    const config = JSON.parse(stripJsonComments(configContent)) as SourcebotConfig;
    const isValidConfig = ajv.validate(indexSchema, config);
    if (!isValidConfig) {
        throw new Error(`Config file '${configPath}' is invalid: ${ajv.errorsText(ajv.errors)}`);
    }
    return config;
}