package service

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"os"
	"time"

	"github.com/hireme/hireme/internal/analyzer"
	"github.com/hireme/hireme/internal/crawler"
	"github.com/hireme/hireme/internal/db"
	"github.com/hireme/hireme/internal/filter"
	"github.com/hireme/hireme/pkg/crawler/google"
	"gopkg.in/yaml.v3"
)

type TargetConfigYAML struct {
	Targets []struct {
		Name      string `yaml:"name"`
		TargetURL string `yaml:"target_url"`
		Platform  string `yaml:"platform"`
		IsActive  bool   `yaml:"is_active"`
	} `yaml:"targets"`
}

type PipelineService struct {
	db          *db.DB
	crawlers    []crawler.SiteCrawler
	filterPipe  *filter.FilterPipeline
	llmAnalyzer analyzer.LLMAnalyzer
}

func NewPipelineService(database *db.DB, llmAnalyzer analyzer.LLMAnalyzer) *PipelineService {
	hardFilter := filter.NewHardKeywordFilter(nil)
	scoringFilter := filter.NewScoringFilter(nil)
	pipeline := filter.NewPipeline(hardFilter, scoringFilter)

	crawlers := []crawler.SiteCrawler{
		google.NewGoogleCrawler(),
		crawler.NewGenericCrawler(),
	}

	return &PipelineService{
		db:          database,
		crawlers:    crawlers,
		filterPipe:  pipeline,
		llmAnalyzer: llmAnalyzer,
	}
}

// LoadTargetsFromYAML loads search targets from YAML configuration file if DB targets table is empty
func (s *PipelineService) LoadTargetsFromYAML(yamlPath string) error {
	targets, err := s.db.GetAllTargets()
	if err != nil {
		return err
	}
	if len(targets) > 0 {
		return nil
	}

	data, err := os.ReadFile(yamlPath)
	if err != nil {
		return fmt.Errorf("could not read targets YAML config at %s: %w", yamlPath, err)
	}

	var configData TargetConfigYAML
	if err := yaml.Unmarshal(data, &configData); err != nil {
		return fmt.Errorf("failed to parse YAML targets config: %w", err)
	}

	for _, t := range configData.Targets {
		_, err := s.db.CreateTarget(t.Name, t.TargetURL, t.Platform)
		if err != nil {
			log.Printf("[Pipeline] Error loading target %s: %v", t.Name, err)
		}
	}

	log.Printf("[Pipeline] Loaded %d search targets from YAML config (%s)", len(configData.Targets), yamlPath)
	return nil
}

func (s *PipelineService) getCrawlerForPlatform(platform string) crawler.SiteCrawler {
	for _, c := range s.crawlers {
		if c.CanHandle(platform) {
			return c
		}
	}
	return s.crawlers[len(s.crawlers)-1] // fallback to generic
}

// RunPipeline executes Stage 1 (Ingestion) and Stage 2 (Filtering & LLM Enrichment)
func (s *PipelineService) RunPipeline(ctx context.Context) (int, int, error) {
	log.Println("[Pipeline] Starting ingestion & processing run...")

	// 1. Fetch active targets
	targets, err := s.db.GetActiveTargets()
	if err != nil {
		return 0, 0, fmt.Errorf("failed to get active targets: %w", err)
	}

	newJobsCount := 0
	for _, target := range targets {
		log.Printf("[Pipeline] Discovering jobs for target #%d: %s (%s)", target.ID, target.Name, target.TargetURL)
		c := s.getCrawlerForPlatform(target.Platform)
		discovered, err := c.DiscoverJobs(ctx, target.TargetURL)
		if err != nil {
			log.Printf("[Pipeline] DiscoverJobs error for target #%d: %v", target.ID, err)
			continue
		}

		log.Printf("[Pipeline] Discovered %d potential job links for target #%d", len(discovered), target.ID)

		for _, disc := range discovered {
			// Check DB deduplication first
			exists, err := s.db.CanonicalIDExists(disc.CanonicalID)
			if err == nil && exists {
				continue // Skip existing job link!
			}

			// Fetch & parse detail page for new job only
			extracted, err := c.FetchJobDetail(ctx, disc.ApplyURL)
			if err != nil {
				log.Printf("[Pipeline] FetchJobDetail error for %s: %v", disc.ApplyURL, err)
				continue
			}

			tID := target.ID
			_, inserted, err := s.db.InsertRawJob(extracted.CanonicalID, &tID, extracted.Title, extracted.Company, extracted.Location, extracted.ApplyURL, extracted.RawContent)
			if err != nil {
				log.Printf("[Pipeline] Error inserting job %s: %v", extracted.Title, err)
				continue
			}
			if inserted {
				newJobsCount++
			}

			// Polite delay to prevent HTTP 429 rate-limiting from Google
			time.Sleep(500 * time.Millisecond)
		}

		_ = s.db.UpdateTargetCrawledAt(target.ID)
	}

	// 2. Execute Stage 2 Filter Pipeline on pending raw_jobs
	pendingJobs, err := s.db.GetPendingRawJobs()
	if err != nil {
		return newJobsCount, 0, fmt.Errorf("failed to fetch pending jobs: %w", err)
	}

	qualifiedCount := 0
	for _, job := range pendingJobs {
		keep, score := s.filterPipe.Execute(ctx, job.Title, job.RawContent)

		if !keep {
			log.Printf("[Pipeline] Job #%d (%s) FILTERED OUT by keyword pipeline", job.ID, job.Title)
			_ = s.db.CreateJobAnalysis(job.ID, 0, false, "FILTERED_OUT")
			_ = s.db.UpdateRawJobStatus(job.ID, "PROCESSED")
			continue
		}

		log.Printf("[Pipeline] Job #%d (%s) PASSED filter with score %.2f", job.ID, job.Title, score)
		_ = s.db.CreateJobAnalysis(job.ID, score, true, "PENDING")
		_ = s.db.UpdateRawJobStatus(job.ID, "PROCESSED")
		qualifiedCount++
	}

	// 3. Trigger LLM Analysis on qualified PENDING analyses
	pendingAnalyses, err := s.db.GetPendingQualifiedAnalyses()
	if err != nil {
		log.Printf("[Pipeline] Error fetching pending qualified analyses: %v", err)
		return newJobsCount, qualifiedCount, nil
	}

	for _, item := range pendingAnalyses {
		log.Printf("[Pipeline] Triggering LLM analysis for Job #%d (%s @ %s)...", item.ID, item.Title, item.Company)
		output, err := s.llmAnalyzer.AnalyzeJD(ctx, item.Title, item.RawContent)
		if err != nil {
			log.Printf("[Pipeline] LLM analysis failed for job #%d: %v", item.ID, err)
			continue
		}

		matchedJSON, _ := json.Marshal(output.MatchedHighlights)
		missingJSON, _ := json.Marshal(output.MissingHighlights)
		suggestionsJSON, _ := json.Marshal(output.TailoringSuggestions)

		err = s.db.UpdateJobAnalysisLLM(item.ID, string(matchedJSON), string(missingJSON), string(suggestionsJSON))
		if err != nil {
			log.Printf("[Pipeline] Failed to save LLM analysis for job #%d: %v", item.ID, err)
		} else {
			log.Printf("[Pipeline] Successfully cached LLM analysis for Job #%d", item.ID)
		}
	}

	return newJobsCount, qualifiedCount, nil
}

// AnalyzeJobByID manually triggers LLM analysis on a single job
func (s *PipelineService) AnalyzeJobByID(ctx context.Context, jobID int64) (*db.JobWithAnalysis, error) {
	jobWithAnalysis, err := s.db.GetJobByID(jobID)
	if err != nil {
		return nil, err
	}

	output, err := s.llmAnalyzer.AnalyzeJD(ctx, jobWithAnalysis.Title, jobWithAnalysis.RawContent)
	if err != nil {
		return nil, fmt.Errorf("LLM analysis failed: %w", err)
	}

	matchedJSON, _ := json.Marshal(output.MatchedHighlights)
	missingJSON, _ := json.Marshal(output.MissingHighlights)
	suggestionsJSON, _ := json.Marshal(output.TailoringSuggestions)

	if jobWithAnalysis.Analysis == nil {
		_, score := s.filterPipe.Execute(ctx, jobWithAnalysis.Title, jobWithAnalysis.RawContent)
		_ = s.db.CreateJobAnalysis(jobID, score, true, "PENDING")
	}

	err = s.db.UpdateJobAnalysisLLM(jobID, string(matchedJSON), string(missingJSON), string(suggestionsJSON))
	if err != nil {
		return nil, err
	}

	return s.db.GetJobByID(jobID)
}