qubit-progress 0.8.1

// =============================================================================
//    Copyright (c) 2025 - 2026 Haixing Hu.
//
//    SPDX-License-Identifier: Apache-2.0
//
//    Licensed under the Apache License, Version 2.0.
// =============================================================================
//! Shared validation for operation configuration and report snapshots.
// qubit-style: allow type-file-name

use std::collections::HashSet;

use crate::{
    ConfigurationError,
    Metric,
    OperationAttributes,
    Stage,
};

#[cfg(feature = "serde")]
use crate::MetricSnapshot;

/// Validates the fixed metric configuration for one operation.
pub(crate) fn validate_metrics(
    metrics: &[Metric],
) -> Result<(), ConfigurationError> {
    if metrics.is_empty() {
        return Err(ConfigurationError::NoMetrics);
    }
    let mut ids = HashSet::with_capacity(metrics.len());
    for (index, metric) in metrics.iter().enumerate() {
        if metric.id.trim().is_empty() {
            return Err(ConfigurationError::EmptyMetricId { index });
        }
        if metric.name.trim().is_empty() {
            return Err(ConfigurationError::EmptyMetricName {
                metric_id: metric.id.to_string(),
            });
        }
        if !ids.insert(&metric.id) {
            return Err(ConfigurationError::DuplicateMetricId {
                metric_id: metric.id.to_string(),
            });
        }
    }
    Ok(())
}

/// Validates optional stage metadata.
pub(crate) fn validate_stage(stage: &Stage) -> Result<(), ConfigurationError> {
    if stage.id.trim().is_empty() {
        return Err(ConfigurationError::EmptyStageId);
    }
    if stage.name.trim().is_empty() {
        return Err(ConfigurationError::EmptyStageName);
    }
    match (stage.position, stage.total) {
        (None, None) => Ok(()),
        (Some(position), Some(total)) if position > 0 && position <= total => {
            Ok(())
        }
        (Some(position), Some(total)) => {
            Err(ConfigurationError::InvalidStagePosition { position, total })
        }
        _ => Err(ConfigurationError::IncompleteStagePosition),
    }
}

/// Validates operation correlation attribute keys.
pub(crate) fn validate_attributes(
    attributes: &OperationAttributes,
) -> Result<(), ConfigurationError> {
    if let Some((key, _)) =
        attributes.iter().find(|(key, _)| key.trim().is_empty())
    {
        return Err(ConfigurationError::EmptyAttributeKey {
            key: key.to_owned(),
        });
    }
    Ok(())
}

/// Validates one metric's dynamic counts against its configured total.
#[cfg(feature = "serde")]
pub(crate) fn validate_snapshot_counts(
    snapshot: &MetricSnapshot,
) -> Result<(), SnapshotValidationError> {
    let classified = snapshot
        .succeeded()
        .checked_add(snapshot.failed())
        .and_then(|value| value.checked_add(snapshot.cancelled()))
        .ok_or_else(|| SnapshotValidationError::CountOverflow {
            metric_id: snapshot.id().into(),
        })?;
    if classified > snapshot.completed() {
        return Err(SnapshotValidationError::ClassifiedExceedsCompleted {
            metric_id: snapshot.id().into(),
        });
    }
    if let Some(total) = snapshot.total() {
        if total == 0
            && (snapshot.completed() != 0
                || snapshot.active() != 0
                || snapshot.succeeded() != 0
                || snapshot.failed() != 0
                || snapshot.cancelled() != 0)
        {
            return Err(SnapshotValidationError::NonZeroCountsForZeroTotal {
                metric_id: snapshot.id().into(),
            });
        }
        let occupied = snapshot
            .completed()
            .checked_add(snapshot.active())
            .ok_or_else(|| SnapshotValidationError::CountOverflow {
                metric_id: snapshot.id().into(),
            })?;
        if occupied > total {
            return Err(SnapshotValidationError::CountsExceedTotal {
                metric_id: snapshot.id().into(),
            });
        }
    }
    Ok(())
}

/// Validation failure for serialized dynamic metric counts.
#[cfg(feature = "serde")]
#[derive(Debug)]
pub(crate) enum SnapshotValidationError {
    /// Derived classified counts overflowed.
    CountOverflow { metric_id: String },
    /// Classified counts exceed completed work.
    ClassifiedExceedsCompleted { metric_id: String },
    /// Occupied work exceeds a known total.
    CountsExceedTotal { metric_id: String },
    /// A zero total contains dynamic counts.
    NonZeroCountsForZeroTotal { metric_id: String },
}

#[cfg(feature = "serde")]
impl std::fmt::Display for SnapshotValidationError {
    /// Formats the snapshot validation failure.
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::CountOverflow { metric_id } => {
                write!(formatter, "counts for metric {metric_id:?} overflowed")
            }
            Self::ClassifiedExceedsCompleted { metric_id } => write!(
                formatter,
                "classified counts exceed completed work for metric {metric_id:?}"
            ),
            Self::CountsExceedTotal { metric_id } => write!(
                formatter,
                "completed plus active work exceeds total for metric {metric_id:?}"
            ),
            Self::NonZeroCountsForZeroTotal { metric_id } => write!(
                formatter,
                "zero-total metric {metric_id:?} has nonzero counts"
            ),
        }
    }
}

#[cfg(feature = "serde")]
impl std::error::Error for SnapshotValidationError {}