package validators

import (
	"context"
	"fmt"
	"strings"
)

type ConfidenceThresholdValidator struct{}

func (v ConfidenceThresholdValidator) Name() string { return "confidence_threshold" }

func (v ConfidenceThresholdValidator) Validate(_ context.Context, req Request) (Result, error) {
	threshold := confidenceThresholdForModule(req.ModuleKey, req.Config)
	decisions := make([]Decision, 0, len(req.CandidateProposal))
	for _, c := range req.CandidateProposal {
		if c.Confidence < threshold {
			decisions = append(decisions, rejection(c.ProposalIndex, ReasonLowConfidence, fmt.Sprintf("confidence %.4f below threshold %.4f", c.Confidence, threshold)))
			continue
		}
		decisions = append(decisions, approval(c.ProposalIndex))
	}
	if err := EnforceDecisionCardinality(req.CandidateProposal, decisions); err != nil {
		return Result{}, err
	}
	return Result{ValidatorName: v.Name(), Decisions: decisions}, nil
}

type OriginalTextPresenceValidator struct{}

func (v OriginalTextPresenceValidator) Name() string { return "original_text_presence" }

func (v OriginalTextPresenceValidator) Validate(_ context.Context, req Request) (Result, error) {
	byID := make(map[int]string)
	if req.WorkingTranscript != nil {
		for _, seg := range req.WorkingTranscript.Segments {
			byID[seg.ID] = seg.Text
		}
	}

	decisions := make([]Decision, 0, len(req.CandidateProposal))
	for _, c := range req.CandidateProposal {
		text, ok := byID[c.TargetSegmentID]
		if !ok {
			decisions = append(decisions, rejection(c.ProposalIndex, ReasonMissingTargetSegment, "target segment was not found"))
			continue
		}
		if !strings.Contains(text, c.OriginalText) {
			decisions = append(decisions, rejection(c.ProposalIndex, ReasonMissingOriginalText, "original_text was not found in current segment text"))
			continue
		}
		decisions = append(decisions, approval(c.ProposalIndex))
	}
	if err := EnforceDecisionCardinality(req.CandidateProposal, decisions); err != nil {
		return Result{}, err
	}
	return Result{ValidatorName: v.Name(), Decisions: decisions}, nil
}

type NonEmptyCorrectionValidator struct{}

func (v NonEmptyCorrectionValidator) Name() string { return "non_empty_correction" }

func (v NonEmptyCorrectionValidator) Validate(_ context.Context, req Request) (Result, error) {
	decisions := make([]Decision, 0, len(req.CandidateProposal))
	for _, c := range req.CandidateProposal {
		if strings.TrimSpace(c.CorrectedText) == "" {
			decisions = append(decisions, rejection(c.ProposalIndex, ReasonEmptyCorrectedText, "corrected_text must not be empty"))
			continue
		}
		decisions = append(decisions, approval(c.ProposalIndex))
	}
	if err := EnforceDecisionCardinality(req.CandidateProposal, decisions); err != nil {
		return Result{}, err
	}
	return Result{ValidatorName: v.Name(), Decisions: decisions}, nil
}

type NoEffectValidator struct{}

func (v NoEffectValidator) Name() string { return "no_effect" }

func (v NoEffectValidator) Validate(_ context.Context, req Request) (Result, error) {
	decisions := make([]Decision, 0, len(req.CandidateProposal))
	for _, c := range req.CandidateProposal {
		if c.OriginalText == c.CorrectedText {
			decisions = append(decisions, rejection(c.ProposalIndex, ReasonNoEffect, "original_text and corrected_text are identical"))
			continue
		}
		decisions = append(decisions, approval(c.ProposalIndex))
	}
	if err := EnforceDecisionCardinality(req.CandidateProposal, decisions); err != nil {
		return Result{}, err
	}
	return Result{ValidatorName: v.Name(), Decisions: decisions}, nil
}

type ProtectedGlossaryTermValidator struct{}

func (v ProtectedGlossaryTermValidator) Name() string { return "protected_glossary_terms" }

func (v ProtectedGlossaryTermValidator) Validate(_ context.Context, req Request) (Result, error) {
	if req.ModuleKey == "glossary" {
		decisions := make([]Decision, 0, len(req.CandidateProposal))
		for _, c := range req.CandidateProposal {
			decisions = append(decisions, approval(c.ProposalIndex))
		}
		return Result{ValidatorName: v.Name(), Decisions: decisions}, nil
	}

	vocab := NewProtectedVocabulary(req.Glossary)
	decisions := make([]Decision, 0, len(req.CandidateProposal))
	for _, c := range req.CandidateProposal {
		reason := vocab.violationReason(c.OriginalText, c.CorrectedText)
		if reason != "" {
			decisions = append(decisions, rejection(c.ProposalIndex, ReasonProtectedGlossaryTerm, reason))
			continue
		}
		decisions = append(decisions, approval(c.ProposalIndex))
	}
	if err := EnforceDecisionCardinality(req.CandidateProposal, decisions); err != nil {
		return Result{}, err
	}
	return Result{ValidatorName: v.Name(), Decisions: decisions}, nil
}

type GlossaryStageProtectedGlossaryTermValidator struct{}

func (v GlossaryStageProtectedGlossaryTermValidator) Name() string {
	return "glossary_stage_protected_glossary_terms"
}

func (v GlossaryStageProtectedGlossaryTermValidator) Validate(_ context.Context, req Request) (Result, error) {
	vocab := NewProtectedVocabulary(req.Glossary)
	decisions := make([]Decision, 0, len(req.CandidateProposal))
	for _, c := range req.CandidateProposal {
		reason := vocab.glossaryStageViolationReason(c.OriginalText, c.CorrectedText)
		if reason != "" {
			decisions = append(decisions, rejection(c.ProposalIndex, ReasonProtectedGlossaryTerm, reason))
			continue
		}
		decisions = append(decisions, approval(c.ProposalIndex))
	}
	if err := EnforceDecisionCardinality(req.CandidateProposal, decisions); err != nil {
		return Result{}, err
	}
	return Result{ValidatorName: v.Name(), Decisions: decisions}, nil
}