aidio-description/src/utils/costEstimator.ts

import { Config } from '../config/config';
import { CostBreakdown } from '../interfaces';
import { getVideoDuration } from './mediaUtils';

/**
 * Estimate the cost of generating audio descriptions for a video
 * @param videoFilePath - Path to the input video file
 * @param options - Optional configuration overrides
 * @returns Cost estimation breakdown
 */
export async function estimateCost(
  videoFilePath: string, 
  options: Partial<Config> = {}
): Promise<CostBreakdown> {
  // Merge provided options with defaults
  const settings = { ...options } as Config;

  // Get video duration
  const videoDuration = getVideoDuration(videoFilePath);
  console.log(`Video duration: ${videoDuration} seconds`);

  // Calculate the number of frames or batches to process
  let totalUnits: number;
  let unitCostMultiplier: number;
  let unitType: string;
  
  if (settings.batchTimeMode) {
    totalUnits = Math.floor(videoDuration / settings.batchWindowDuration);
    unitCostMultiplier = settings.framesInBatch; // Cost multiplier for batch mode
    unitType = "batches";
  } else {
    totalUnits = Math.floor(videoDuration / settings.captureIntervalSeconds);
    unitCostMultiplier = 1; // No multiplier for normal mode
    unitType = "frames";
  }
  
  console.log(`Will process ${totalUnits} ${unitType}`);

  // Pricing constants (as of March 2025, update as needed)
  const pricing: {
    vision: Record<string, Record<string, { input: number; output: number }>>;
    tts: Record<string, Record<string, number>>;
  } = {
    vision: {
      openai: {
        'gpt-4o': {
          input: 0.0025,
          output: 0.01
        }
      },
      gemini: {
        'gemini-pro-vision': {
          input: 0.0025,
          output: 0.0025
        }
      }
    },
    tts: {
      openai: {
        'tts-1': 0.015,
        'tts-1-hd': 0.030
      }
    }
  };

  // Get the pricing for the selected providers
  const visionProvider = settings.visionProvider;
  const visionModel = settings.visionProviders[visionProvider].model;
  const ttsProvider = settings.ttsProvider;
  const ttsModel = settings.ttsProviders[ttsProvider].model;

  // Check if the pricing data exists
  const visionPricing = pricing.vision[visionProvider]?.[visionModel];
  const ttsPricing = pricing.tts[ttsProvider]?.[ttsModel];

  if (!visionPricing) {
    console.warn(`Warning: No pricing data for vision provider "${visionProvider}" and model "${visionModel}".`);
  }

  if (!ttsPricing) {
    console.warn(`Warning: No pricing data for TTS provider "${ttsProvider}" and model "${ttsModel}".`);
  }

  // Estimated token counts
  const estimatedVisionInputTokens = 1000 * unitCostMultiplier; // Base tokens for the vision input
  const estimatedPromptTokens = 100; // Tokens for the prompt text
  const estimatedOutputTokensPerUnit = 75; // Average tokens for description output

  // Estimated character counts for TTS
  const estimatedCharsPerDescription = 200; // Average characters per description

  // Calculate estimated costs for first unit
  const firstUnitCost = {
    visionInput: (estimatedVisionInputTokens + estimatedPromptTokens) * (visionPricing?.input || 0) / 1000,
    visionOutput: estimatedOutputTokensPerUnit * (visionPricing?.output || 0) / 1000,
    tts: estimatedCharsPerDescription * (ttsPricing || 0) / 1000
  };

  // For subsequent units, we need context (e.g., previous frames)
  const contextMultiplier = settings.batchTimeMode ? 1.2 : 2; // Less overhead in batch mode
  
  const subsequentUnitCost = {
    visionInput: (estimatedVisionInputTokens * contextMultiplier + estimatedPromptTokens) * (visionPricing?.input || 0) / 1000,
    visionOutput: estimatedOutputTokensPerUnit * (visionPricing?.output || 0) / 1000,
    tts: estimatedCharsPerDescription * (ttsPricing || 0) / 1000
  };

  // Calculate total costs
  const totalVisionInputCost =
    firstUnitCost.visionInput +
    (totalUnits - 1) * subsequentUnitCost.visionInput;

  const totalVisionOutputCost =
    firstUnitCost.visionOutput +
    (totalUnits - 1) * subsequentUnitCost.visionOutput;

  const totalTTSCost =
    firstUnitCost.tts +
    (totalUnits - 1) * subsequentUnitCost.tts;

  const totalCost = totalVisionInputCost + totalVisionOutputCost + totalTTSCost;

  // Create cost breakdown
  const costBreakdown: CostBreakdown = {
    videoInfo: {
      duration: videoDuration,
      totalUnits: totalUnits,
      unitType: unitType,
      processingInterval: settings.batchTimeMode ? settings.batchWindowDuration : settings.captureIntervalSeconds
    },
    providerInfo: {
      visionProvider: visionProvider,
      visionModel: visionModel,
      ttsProvider: ttsProvider,
      ttsModel: ttsModel
    },
    apiCosts: {
      visionInput: totalVisionInputCost.toFixed(4),
      visionOutput: totalVisionOutputCost.toFixed(4),
      tts: totalTTSCost.toFixed(4),
      total: totalCost.toFixed(4)
    },
    estimates: {
      totalAPICallsToProviders: totalUnits * 2, // Vision + TTS for each unit
      estimatedProcessingTimeMinutes: (totalUnits * 3) / 60 // rough estimate, 3 seconds per unit
    }
  };

  return costBreakdown;
}