package gudusoft.gsqlparser.lineage2.contract;

/**
 * Contract {@code Edge} (lineage2-contract.md §4) — the atomic lineage
 * assertion: <em>source endpoint influences target endpoint in manner
 * {@code role}</em>.
 *
 * <p>{@code source} is nullable exclusively for {@code role: DERIVED}
 * (constant-only / synthesized targets); the identity layer treats a null
 * source as empty strings for all source components per rev-3
 * normalization. {@code rowLevel} is derived: {@code true} iff
 * {@code axis == ROW}.
 *
 * <p>Internal API: not part of the public gsqlparser surface.
 */
public final class ContractEdge {

    private final Endpoint source;
    private final Endpoint target;
    private final LineageRole role;
    private final LineageAxis axis;
    private final EvaluationModel evaluationModel;
    private final CaseBranch caseBranch;
    private final boolean dynamic;
    private final double confidence;
    private final int statementIndex;
    private final Transformation transformation;
    private final EdgeIdentity identity;

    private ContractEdge(Builder b) {
        if (b.target == null) {
            throw new IllegalArgumentException("target must not be null");
        }
        if (b.role == null || b.axis == null || b.evaluationModel == null) {
            throw new IllegalArgumentException(
                    "role, axis, and evaluationModel must not be null");
        }
        if (b.source == null && b.role != LineageRole.DERIVED) {
            throw new IllegalArgumentException(
                    "source is nullable exclusively for role DERIVED; got " + b.role);
        }
        if (b.identity == null) {
            throw new IllegalArgumentException("identity must not be null");
        }
        this.source = b.source;
        this.target = b.target;
        this.role = b.role;
        this.axis = b.axis;
        this.evaluationModel = b.evaluationModel;
        this.caseBranch = b.caseBranch;
        this.dynamic = b.dynamic;
        this.confidence = b.confidence;
        this.statementIndex = b.statementIndex;
        this.transformation = b.transformation;
        this.identity = b.identity;
    }

    public static Builder builder() {
        return new Builder();
    }

    /** Nullable exclusively for {@code role: DERIVED}. */
    public Endpoint getSource() {
        return source;
    }

    public Endpoint getTarget() {
        return target;
    }

    public LineageRole getRole() {
        return role;
    }

    public LineageAxis getAxis() {
        return axis;
    }

    public EvaluationModel getEvaluationModel() {
        return evaluationModel;
    }

    /** Contract invariant: {@code rowLevel} is true iff axis is ROW. */
    public boolean isRowLevel() {
        return axis == LineageAxis.ROW;
    }

    /** Nullable. */
    public CaseBranch getCaseBranch() {
        return caseBranch;
    }

    public boolean isDynamic() {
        return dynamic;
    }

    public double getConfidence() {
        return confidence;
    }

    public int getStatementIndex() {
        return statementIndex;
    }

    /** Nullable — omitted on pure-copy DIRECT edges. */
    public Transformation getTransformation() {
        return transformation;
    }

    public EdgeIdentity getIdentity() {
        return identity;
    }

    public static final class Builder {
        private Endpoint source;
        private Endpoint target;
        private LineageRole role;
        private LineageAxis axis;
        private EvaluationModel evaluationModel = EvaluationModel.EXACT;
        private CaseBranch caseBranch;
        private boolean dynamic;
        private double confidence = 1.0;
        private int statementIndex = 1;
        private Transformation transformation;
        private EdgeIdentity identity;

        private Builder() {}

        public Builder source(Endpoint source) {
            this.source = source;
            return this;
        }

        public Builder target(Endpoint target) {
            this.target = target;
            return this;
        }

        public Builder role(LineageRole role) {
            this.role = role;
            return this;
        }

        public Builder axis(LineageAxis axis) {
            this.axis = axis;
            return this;
        }

        public Builder evaluationModel(EvaluationModel evaluationModel) {
            this.evaluationModel = evaluationModel;
            return this;
        }

        public Builder caseBranch(CaseBranch caseBranch) {
            this.caseBranch = caseBranch;
            return this;
        }

        public Builder dynamic(boolean dynamic) {
            this.dynamic = dynamic;
            return this;
        }

        public Builder confidence(double confidence) {
            this.confidence = confidence;
            return this;
        }

        public Builder statementIndex(int statementIndex) {
            this.statementIndex = statementIndex;
            return this;
        }

        public Builder transformation(Transformation transformation) {
            this.transformation = transformation;
            return this;
        }

        public Builder identity(EdgeIdentity identity) {
            this.identity = identity;
            return this;
        }

        public ContractEdge build() {
            return new ContractEdge(this);
        }
    }
}