/**
 * Copyright 2024 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import { PromptAction } from '@genkit-ai/ai';
import { GenkitError } from '@genkit-ai/core';
import { logger } from '@genkit-ai/core/logging';
import { Registry } from '@genkit-ai/core/registry';
import { existsSync, readdir, readFileSync } from 'fs';
import { basename, join, resolve } from 'path';
import { Dotprompt } from './prompt.js';
import { definePartial } from './template.js';

export function registryDefinitionKey(
  name: string,
  variant?: string,
  ns?: string
) {
  // "ns/prompt.variant" where ns and variant are optional
  return `${ns ? `${ns}/` : ''}${name}${variant ? `.${variant}` : ''}`;
}

export function registryLookupKey(name: string, variant?: string, ns?: string) {
  return `/prompt/${registryDefinitionKey(name, variant, ns)}`;
}

export async function lookupPrompt(
  registry: Registry,
  name: string,
  variant?: string,
  dir: string = './prompts'
): Promise<Dotprompt> {
  let registryPrompt =
    (await registry.lookupAction(registryLookupKey(name, variant))) ||
    (await registry.lookupAction(
      registryLookupKey(name, variant, 'dotprompt')
    ));
  if (registryPrompt) {
    return Dotprompt.fromAction(registry, registryPrompt as PromptAction);
  } else {
    // Handle the case where initialization isn't complete
    // or a file was added after the prompt folder was loaded.
    return maybeLoadPrompt(registry, dir, name, variant);
  }
}

async function maybeLoadPrompt(
  registry: Registry,
  dir: string,
  name: string,
  variant?: string
): Promise<Dotprompt> {
  const expectedFileName = `${name}${variant ? `.${variant}` : ''}.prompt`;
  const promptFolder = resolve(dir);
  const promptExists = existsSync(join(promptFolder, expectedFileName));
  if (promptExists) {
    return loadPrompt(registry, promptFolder, expectedFileName);
  } else {
    throw new GenkitError({
      source: 'dotprompt',
      status: 'NOT_FOUND',
      message: `Could not find '${expectedFileName}' in the prompts folder.`,
    });
  }
}

export async function loadPromptFolder(
  registry: Registry,
  dir: string = './prompts',
  ns: string
): Promise<void> {
  const promptsPath = resolve(dir);
  return new Promise<void>((resolve, reject) => {
    if (existsSync(promptsPath)) {
      readdir(
        promptsPath,
        {
          withFileTypes: true,
          recursive: true,
        },
        (err, dirEnts) => {
          if (err) {
            reject(err);
          } else {
            dirEnts.forEach(async (dirEnt) => {
              if (dirEnt.isFile() && dirEnt.name.endsWith('.prompt')) {
                if (dirEnt.name.startsWith('_')) {
                  const partialName = dirEnt.name.substring(
                    1,
                    dirEnt.name.length - 7
                  );
                  definePartial(
                    partialName,
                    readFileSync(join(dirEnt.path, dirEnt.name), {
                      encoding: 'utf8',
                    })
                  );
                  logger.debug(
                    `Registered Dotprompt partial "${partialName}" from "${join(dirEnt.path, dirEnt.name)}"`
                  );
                } else {
                  // If this prompt is in a subdirectory, we need to include that
                  // in the namespace to prevent naming conflicts.
                  let prefix = '';
                  if (promptsPath !== dirEnt.path) {
                    prefix = dirEnt.path
                      .replace(`${promptsPath}/`, '')
                      .replace(/\//g, '-');
                  }
                  loadPrompt(registry, dirEnt.path, dirEnt.name, prefix, ns);
                }
              }
            });
            resolve();
          }
        }
      );
    } else {
      resolve();
    }
  });
}

export function loadPrompt(
  registry: Registry,
  path: string,
  filename: string,
  prefix = '',
  ns = 'dotprompt'
): Dotprompt {
  let name = `${prefix ? `${prefix}-` : ''}${basename(filename, '.prompt')}`;
  let variant: string | null = null;
  if (name.includes('.')) {
    const parts = name.split('.');
    name = parts[0];
    variant = parts[1];
  }
  const source = readFileSync(join(path, filename), 'utf8');
  const prompt = Dotprompt.parse(registry, name, source);
  if (variant) {
    prompt.variant = variant;
  }
  prompt.define({ ns });
  return prompt;
}