package event

import (
	"context"
	"fmt"

	"github.com/rs/zerolog"

	"github.com/vincentc-afk/gitea-notification-hub/internal/identity"
	"github.com/vincentc-afk/gitea-notification-hub/internal/slack"
	"github.com/vincentc-afk/gitea-notification-hub/internal/webhook"
)

// Processor handles processing of webhook events
type Processor struct {
	resolver identity.Resolver
	slack    slack.Client
	logger   zerolog.Logger
}

// NewProcessor creates a new event processor
func NewProcessor(resolver identity.Resolver, slackClient slack.Client, logger zerolog.Logger) *Processor {
	return &Processor{
		resolver: resolver,
		slack:    slackClient,
		logger:   logger.With().Str("component", "processor").Logger(),
	}
}

// ProcessPullRequest handles pull_request webhook events
func (p *Processor) ProcessPullRequest(ctx context.Context, event *webhook.PullRequestEvent) error {
	logger := p.logger.With().
		Int64("pr_number", event.Number).
		Str("action", event.Action).
		Str("repo", event.Repository.FullName).
		Logger()

	logger.Info().Msg("processing pull request event")

	switch event.Action {
	case "review_requested":
		return p.handleReviewRequested(ctx, event, logger)
	case "opened":
		return p.handleOpened(ctx, event, logger)
	case "closed":
		return p.handleClosed(ctx, event, logger)
	default:
		logger.Debug().Msg("ignoring pull_request action")
		return nil
	}
}

// handleReviewRequested processes review_requested events
func (p *Processor) handleReviewRequested(ctx context.Context, event *webhook.PullRequestEvent, logger zerolog.Logger) error {
	logger.Info().Msg("processing review_requested event")

	var reviewer *webhook.GiteaUser

	// Approach 1: event.RequestedReviewers array (standard)
	if len(event.RequestedReviewers) > 0 {
		reviewer = &event.RequestedReviewers[0]
		logger.Info().
			Int("count", len(event.RequestedReviewers)).
			Str("reviewer", reviewer.Login).
			Msg("found reviewer in RequestedReviewers array")
	} else if event.RequestedReviewer != nil {
		// Approach 2: singular field (edge case)
		reviewer = event.RequestedReviewer
		logger.Info().
			Str("reviewer", reviewer.Login).
			Msg("found reviewer in RequestedReviewer singular field")
	} else if len(event.PullRequest.Assignees) > 0 {
		// Approach 3: fall back to PR assignees
		reviewer = &event.PullRequest.Assignees[0]
		logger.Info().
			Str("reviewer", reviewer.Login).
			Msg("falling back to PR assignee as reviewer")
	} else {
		logger.Warn().Msg("no reviewer found in event payload")
		return fmt.Errorf("no reviewer found for review_requested event (PR #%d)", event.Number)
	}

	// Resolve the reviewer's Slack identity
	resolved, err := p.resolver.Resolve(ctx, User{
		GiteaUsername: reviewer.Login,
		GiteaID:       reviewer.ID,
		Email:         reviewer.Email,
		FullName:      reviewer.FullName,
	})
	if err != nil {
		logger.Error().
			Err(err).
			Str("reviewer", reviewer.Login).
			Msg("failed to resolve reviewer identity")
		return fmt.Errorf("resolving reviewer %s: %w", reviewer.Login, err)
	}

	if resolved.SlackID == "" {
		logger.Warn().
			Str("reviewer", reviewer.Login).
			Msg("reviewer has no Slack ID, skipping DM")
		return nil
	}

	// Send Slack DM
	dmText := fmt.Sprintf(
		":bell: *Review Requested*\n*Repository:* %s\n*Pull Request:* #%d - %s\n*Requested by:* %s\n\n<%s|View on Gitea>",
		event.Repository.FullName,
		event.Number,
		event.PullRequest.Title,
		event.Sender.Login,
		event.PullRequest.HTMLURL,
	)

	if err := p.slack.SendDM(ctx, resolved.SlackID, dmText); err != nil {
		logger.Error().
			Err(err).
			Str("slack_id", resolved.SlackID).
			Msg("failed to send Slack DM")
		return fmt.Errorf("sending Slack DM to %s: %w", resolved.SlackID, err)
	}

	logger.Info().
		Str("reviewer", reviewer.Login).
		Str("slack_id", resolved.SlackID).
		Msg("successfully sent review_requested notification")
	return nil
}

// handleOpened processes pull_request opened events
func (p *Processor) handleOpened(ctx context.Context, event *webhook.PullRequestEvent, logger zerolog.Logger) error {
	logger.Info().Msg("processing PR opened event")

	for _, assignee := range event.PullRequest.Assignees {
		resolved, err := p.resolver.Resolve(ctx, User{
			GiteaUsername: assignee.Login,
			GiteaID:       assignee.ID,
			Email:         assignee.Email,
			FullName:      assignee.FullName,
		})
		if err != nil {
			logger.Error().Err(err).Str("assignee", assignee.Login).Msg("failed to resolve assignee")
			continue
		}
		if resolved.SlackID == "" {
			continue
		}
		text := fmt.Sprintf(
			":new: *PR Opened*\n*Repository:* %s\n*PR:* #%d - %s\n*By:* %s\n\n<%s|View on Gitea>",
			event.Repository.FullName,
			event.Number,
			event.PullRequest.Title,
			event.Sender.Login,
			event.PullRequest.HTMLURL,
		)
		if err := p.slack.SendDM(ctx, resolved.SlackID, text); err != nil {
			logger.Error().Err(err).Str("slack_id", resolved.SlackID).Msg("failed to send DM")
		}
	}
	return nil
}

// handleClosed processes pull_request closed/merged events
func (p *Processor) handleClosed(ctx context.Context, event *webhook.PullRequestEvent, logger zerolog.Logger) error {
	if event.PullRequest.Merged {
		logger.Info().Msg("processing PR merged event")
	} else {
		logger.Info().Msg("processing PR closed (without merge) event")
	}

	verb := "Closed"
	if event.PullRequest.Merged {
		verb = "Merged"
	}

	for _, assignee := range event.PullRequest.Assignees {
		resolved, err := p.resolver.Resolve(ctx, User{
			GiteaUsername: assignee.Login,
			GiteaID:       assignee.ID,
			Email:         assignee.Email,
			FullName:      assignee.FullName,
		})
		if err != nil {
			logger.Error().Err(err).Str("assignee", assignee.Login).Msg("failed to resolve assignee")
			continue
		}
		if resolved.SlackID == "" {
			continue
		}
		var emoji string
		if event.PullRequest.Merged {
			emoji = ":white_check_mark:"
		} else {
			emoji = ":x:"
		}
		text := fmt.Sprintf(
			"%s *PR %s*\n*Repository:* %s\n*PR:* #%d - %s\n\n<%s|View on Gitea>",
			emoji,
			verb,
			event.Repository.FullName,
			event.Number,
			event.PullRequest.Title,
			event.PullRequest.HTMLURL,
		)
		if err := p.slack.SendDM(ctx, resolved.SlackID, text); err != nil {
			logger.Error().Err(err).Str("slack_id", resolved.SlackID).Msg("failed to send DM")
		}
	}
	return nil
}