import { serve } from 'https://deno.land/std@0.131.0/http/server.ts'
import { createClient } from 'https://esm.sh/@supabase/supabase-js@2'

const corsHeaders = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Headers': 'authorization, x-client-info, apikey, content-type',
}

interface BatchGeocodingRequest {
  limit?: number
  force_refresh?: boolean
  institute_ids?: string[]
}

interface GeocodingResult {
  institute_id: string
  success: boolean
  message: string
  coordinates?: {
    latitude: number
    longitude: number
    boundingbox: string[]
    geojson?: any
    osm?: any
  }
  error?: string
}

serve(async (req: Request) => {
  // Handle CORS preflight requests
  if (req.method === 'OPTIONS') {
    return new Response('ok', { headers: corsHeaders })
  }

  try {
    // Get environment variables
    const supabaseUrl = Deno.env.get('SUPABASE_URL')
    const supabaseServiceKey = Deno.env.get('SUPABASE_SERVICE_ROLE_KEY')
    const searxngUrl = Deno.env.get('SEARXNG_URL') || 'https://search.kevlarai.com'

    if (!supabaseUrl || !supabaseServiceKey) {
      throw new Error('Missing required environment variables')
    }

    // Create Supabase client
    const supabase = createClient(supabaseUrl, supabaseServiceKey)

    // Parse request body
    const body: BatchGeocodingRequest = await req.json()
    const limit = body.limit || 10
    const forceRefresh = body.force_refresh || false

    // Get institutes that need geocoding
    let query = supabase
      .from('institutes')
      .select('id, name, address, geo_coordinates')
      .not('import_id', 'is', null)

    if (!forceRefresh) {
      // Only get institutes without coordinates or with empty coordinates
      query = query.or('geo_coordinates.is.null,geo_coordinates.eq.{}')
    }

    if (body.institute_ids && body.institute_ids.length > 0) {
      query = query.in('id', body.institute_ids)
    }

    const { data: institutes, error: fetchError } = await query.limit(limit)

    if (fetchError) {
      throw new Error(`Failed to fetch institutes: ${fetchError.message}`)
    }

    if (!institutes || institutes.length === 0) {
      return new Response(
        JSON.stringify({
          success: true,
          message: 'No institutes found that need geocoding',
          processed: 0
        }),
        { 
          status: 200, 
          headers: { ...corsHeaders, 'Content-Type': 'application/json' } 
        }
      )
    }

    console.log(`Processing ${institutes.length} institutes for geocoding`)

    const results: GeocodingResult[] = []
    let successCount = 0
    let errorCount = 0

    // Process institutes sequentially to avoid overwhelming the SearXNG service
    let processedCount = 0
    for (const institute of institutes) {
      try {
        const address = institute.address as any
        if (!address) {
          results.push({
            institute_id: institute.id,
            success: false,
            message: 'No address information available',
            error: 'Missing address data'
          })
          errorCount++
          processedCount++
          continue
        }

        // Build search query from address components
        const addressParts = [
          address.street,
          address.town,
          address.county,
          address.postcode,
          address.country
        ].filter(Boolean)

        if (addressParts.length === 0) {
          results.push({
            institute_id: institute.id,
            success: false,
            message: 'No valid address components found',
            error: 'Empty address parts'
          })
          errorCount++
          processedCount++
          continue
        }

        const searchQuery = addressParts.join(', ')
        console.log(`Geocoding institute ${institute.id}: ${searchQuery}`)

        // Query SearXNG for geocoding with fallback strategy
        const geocodingResult = await geocodeAddressWithFallback(address, searxngUrl)

        if (geocodingResult.success && geocodingResult.coordinates) {
          // Update institute with geospatial coordinates
          const { error: updateError } = await supabase
            .from('institutes')
            .update({
              geo_coordinates: {
                latitude: geocodingResult.coordinates.latitude,
                longitude: geocodingResult.coordinates.longitude,
                boundingbox: geocodingResult.coordinates.boundingbox,
                geojson: geocodingResult.coordinates.geojson,
                osm: geocodingResult.coordinates.osm,
                search_query: searchQuery,
                geocoded_at: new Date().toISOString()
              }
            })
            .eq('id', institute.id)

          if (updateError) {
            throw new Error(`Failed to update institute: ${updateError.message}`)
          }

          results.push({
            institute_id: institute.id,
            success: true,
            message: 'Successfully geocoded',
            coordinates: geocodingResult.coordinates
          })
          successCount++

          // Log the successful geocoding
          await supabase
            .from('function_logs')
            .insert({
              file_id: null,
              step: 'batch_geocoding',
              message: 'Successfully geocoded institute address in batch',
              data: {
                institute_id: institute.id,
                search_query: searchQuery,
                coordinates: geocodingResult.coordinates
              }
            })

        } else {
          results.push({
            institute_id: institute.id,
            success: false,
            message: 'Geocoding failed',
            error: geocodingResult.error || 'Unknown error'
          })
          errorCount++
        }

        processedCount++

        // Add a small delay between requests to be respectful to the SearXNG service
        // Optimize delay based on batch size for better performance
        if (processedCount < institutes.length) {  // Don't delay after the last institute
          const delay = institutes.length > 200 ? 50 : 100;  // Faster processing for large batches
          await new Promise(resolve => setTimeout(resolve, delay))
        }

      } catch (error) {
        console.error(`Error processing institute ${institute.id}:`, error)
        results.push({
          institute_id: institute.id,
          success: false,
          message: 'Processing error',
          error: error.message
        })
        errorCount++
      }
    }

    // Log the batch operation
    await supabase
      .from('function_logs')
      .insert({
        file_id: null,
        step: 'batch_geocoding_complete',
        message: 'Batch geocoding operation completed',
        data: {
          total_processed: institutes.length,
          successful: successCount,
          failed: errorCount,
          results: results
        }
      })

    return new Response(
      JSON.stringify({
        success: true,
        message: 'Batch geocoding completed',
        summary: {
          total_processed: institutes.length,
          successful: successCount,
          failed: errorCount
        },
        results: results
      }),
      { 
        status: 200, 
        headers: { ...corsHeaders, 'Content-Type': 'application/json' } 
      }
    )

  } catch (error) {
    console.error('Error in batch institute geocoder:', error)
    
    return new Response(
      JSON.stringify({ 
        error: 'Internal server error', 
        details: error.message 
      }),
      { 
        status: 500, 
        headers: { ...corsHeaders, 'Content-Type': 'application/json' } 
      }
    )
  }
})

async function geocodeAddress(searchQuery: string, searxngUrl: string): Promise<{
  success: boolean
  coordinates?: {
    latitude: number
    longitude: number
    boundingbox: string[]
    geojson?: any
    osm?: any
  }
  error?: string
}> {
  try {
    // Format search query for OSM
    const osmQuery = `!osm ${searchQuery}`
    const searchUrl = `${searxngUrl}/search?q=${encodeURIComponent(osmQuery)}&format=json`

    const response = await fetch(searchUrl, {
      method: 'GET',
      headers: {
        'Accept': 'application/json',
        'User-Agent': 'ClassroomCopilot-BatchGeocoder/1.0'
      }
    })

    if (!response.ok) {
      throw new Error(`SearXNG request failed: ${response.status} ${response.statusText}`)
    }

    const data = await response.json()

    // Check if we have results - the number_of_results field might be unreliable
    // so we check the results array directly
    if (!data.results || data.results.length === 0) {
      return {
        success: false,
        error: 'No results returned from SearXNG'
      }
    }

    const result = data.results[0]
    
    if (!result.latitude || !result.longitude) {
      return {
        success: false,
        error: 'Missing latitude or longitude in SearXNG response'
      }
    }

    return {
      success: true,
      coordinates: {
        latitude: parseFloat(result.latitude),
        longitude: parseFloat(result.longitude),
        boundingbox: result.boundingbox || [],
        geojson: result.geojson,
        osm: result.osm
      }
    }

  } catch (error) {
    console.error('Geocoding error:', error)
    return {
      success: false,
      error: error.message
    }
  }
}

async function geocodeAddressWithFallback(address: any, searxngUrl: string): Promise<{
  success: boolean
  coordinates?: {
    latitude: number
    longitude: number
    boundingbox: string[]
    geojson?: any
    osm?: any
  }
  error?: string
}> {
  // Strategy 1: Try full address (street + town + county + postcode)
  if (address.street && address.town && address.county && address.postcode) {
    const fullQuery = `${address.street}, ${address.town}, ${address.county}, ${address.postcode}`
    console.log(`Trying full address: ${fullQuery}`)
    
    const result = await geocodeAddress(fullQuery, searxngUrl)
    if (result.success && result.coordinates) {
      console.log('Full address geocoding successful')
      return result
    }
  }
  
  // Strategy 2: Try town + county + postcode
  if (address.town && address.county && address.postcode) {
    const mediumQuery = `${address.town}, ${address.county}, ${address.postcode}`
    console.log(`Trying medium address: ${mediumQuery}`)
    
    const result = await geocodeAddress(mediumQuery, searxngUrl)
    if (result.success && result.coordinates) {
      console.log('Medium address geocoding successful')
      return result
    }
  }
  
  // Strategy 3: Try just postcode
  if (address.postcode) {
    console.log(`Trying postcode only: ${address.postcode}`)
    
    const result = await geocodeAddress(address.postcode, searxngUrl)
    if (result.success && result.coordinates) {
      console.log('Postcode geocoding successful')
      return result
    }
  }
  
  // Strategy 4: Try town + postcode
  if (address.town && address.postcode) {
    const simpleQuery = `${address.town}, ${address.postcode}`
    console.log(`Trying simple address: ${simpleQuery}`)
    
    const result = await geocodeAddress(simpleQuery, searxngUrl)
    if (result.success && result.coordinates) {
      console.log('Simple address geocoding successful')
      return result
    }
  }
  
  // All strategies failed
  return {
    success: false,
    error: 'No coordinates found with any address combination'
  }
}