#![allow(
    clippy::assertions_on_constants,
    clippy::assertions_on_result_states,
    clippy::clone_on_copy,
    clippy::decimal_literal_representation,
    clippy::doc_markdown,
    clippy::empty_line_after_doc_comments,
    clippy::field_reassign_with_default,
    clippy::get_unwrap,
    clippy::identity_op,
    clippy::inconsistent_digit_grouping,
    clippy::indexing_slicing,
    clippy::integer_division,
    clippy::len_zero,
    clippy::let_underscore_must_use,
    clippy::manual_div_ceil,
    clippy::manual_let_else,
    clippy::manual_range_contains,
    clippy::modulo_arithmetic,
    clippy::needless_range_loop,
    clippy::non_ascii_literal,
    clippy::redundant_clone,
    clippy::shadow_reuse,
    clippy::shadow_same,
    clippy::shadow_unrelated,
    clippy::single_match_else,
    clippy::str_to_string,
    clippy::string_slice,
    clippy::tests_outside_test_module,
    clippy::too_many_lines,
    clippy::unnecessary_wraps,
    clippy::unseparated_literal_suffix,
    clippy::use_debug,
    clippy::useless_vec,
    clippy::wildcard_enum_match_arm,
    clippy::else_if_without_else,
    clippy::expect_used,
    clippy::missing_const_for_fn,
    clippy::similar_names,
    clippy::type_complexity,
    clippy::collapsible_else_if,
    clippy::doc_lazy_continuation,
    clippy::items_after_test_module,
    clippy::map_clone,
    clippy::multiple_unsafe_ops_per_block,
    clippy::unwrap_or_default,
    clippy::assign_op_pattern,
    clippy::needless_borrow,
    clippy::println_empty_string,
    clippy::unnecessary_cast,
    clippy::used_underscore_binding,
    clippy::create_dir,
    clippy::implicit_saturating_sub,
    clippy::exit,
    clippy::expect_fun_call,
    clippy::too_many_arguments,
    clippy::unnecessary_map_or,
    clippy::unwrap_used,
    dead_code,
    unused_imports,
    unused_variables,
    clippy::cloned_ref_to_slice_refs,
    clippy::neg_multiply,
    clippy::while_let_loop,
    clippy::bool_assert_comparison,
    clippy::excessive_precision,
    clippy::trivially_copy_pass_by_ref,
    clippy::op_ref,
    clippy::redundant_closure,
    clippy::unnecessary_lazy_evaluations,
    clippy::if_then_some_else_none,
    clippy::unnecessary_to_owned,
    clippy::single_component_path_imports,
)]
//! Multi-episode sequence batching tests
//!
//! These tests verify that `to_sequence_ranges()` correctly handles episode boundaries
//! and prevents hidden state contamination between unrelated episodes.
//!
//! The API was migrated from `to_sequences()` (returning materialized `Sequence` structs)
//! to `to_sequence_ranges()` (returning `SequenceRange` index ranges into the parent batch).
//! Tests now validate via index-based lookups into the `TrajectoryBatch` fields.

use ml::ppo::trajectories::{Trajectory, TrajectoryBatch, TrajectoryStep};
use ml_core::common::action::{ExposureLevel, FactoredAction, OrderType, Urgency};

/// Create a trajectory with specified number of steps
fn create_trajectory(num_steps: usize, state_dim: usize) -> Trajectory {
    let mut trajectory = Trajectory::new();

    for i in 0..num_steps {
        let state = vec![i as f32; state_dim];
        let done = i == num_steps - 1; // Last step is done

        trajectory.add_step(TrajectoryStep {
            state,
            action: FactoredAction::new(ExposureLevel::Flat, OrderType::Market, Urgency::Normal),
            log_prob: -1.0,
            value: 0.5,
            reward: 1.0,
            done,
        });
    }

    trajectory
}

#[test]
fn test_sequence_length_zero_returns_empty() {
    // Test that sequence_length == 0 returns empty (API returns Vec, no panic)
    let episode = create_trajectory(10, 32);
    let advantages = vec![0.1; 10];
    let returns = vec![0.5; 10];

    let batch = TrajectoryBatch::from_trajectories(vec![episode], advantages, returns);

    let sequences = batch.to_sequence_ranges(0);
    assert!(
        sequences.is_empty(),
        "sequence_length=0 should return empty ranges"
    );
}

#[test]
fn test_multi_episode_no_contamination() {
    // Create 3 episodes with different lengths
    let episode1 = create_trajectory(5, 32);   // 5 steps
    let episode2 = create_trajectory(17, 32);  // 17 steps
    let episode3 = create_trajectory(3, 32);   // 3 steps

    // Total: 25 steps
    let total_steps = 5 + 17 + 3;
    let advantages = vec![0.1; total_steps];
    let returns = vec![0.5; total_steps];

    let batch = TrajectoryBatch::from_trajectories(
        vec![episode1, episode2, episode3],
        advantages,
        returns
    );

    let sequences = batch.to_sequence_ranges(8);

    // Verify: No sequence contains steps from multiple episodes.
    // Each sequence range maps into the batch's flattened arrays.
    // The done flags within a sequence should only appear at the last position
    // (if the sequence ends an episode).
    for seq in &sequences {
        let dones_in_range: Vec<(usize, bool)> = (seq.start..seq.end)
            .map(|i| (i - seq.start, batch.dones[i]))
            .collect();

        let done_indices: Vec<usize> = dones_in_range
            .iter()
            .filter(|(_, done)| *done)
            .map(|(i, _)| *i)
            .collect();

        // If a done flag exists, it should ONLY be at the last element
        if !done_indices.is_empty() {
            assert_eq!(
                done_indices.len(), 1,
                "Sequence should have at most 1 done flag (found {})",
                done_indices.len()
            );
            assert_eq!(
                done_indices[0], seq.actual_length - 1,
                "Done flag should be at last position (index {}), found at index {}",
                seq.actual_length - 1, done_indices[0]
            );
        }
    }
}

#[test]
fn test_episode_boundary_state_values() {
    // Create 2 episodes with distinct state values to catch contamination
    let mut episode1 = Trajectory::new();
    for i in 0..5 {
        episode1.add_step(TrajectoryStep {
            state: vec![100.0 + i as f32; 32], // States: 100, 101, 102, 103, 104
            action: FactoredAction::new(ExposureLevel::LongFull, OrderType::Market, Urgency::Normal),
            log_prob: -1.0,
            value: 0.5,
            reward: 1.0,
            done: i == 4, // Last step done
        });
    }

    let mut episode2 = Trajectory::new();
    for i in 0..7 {
        episode2.add_step(TrajectoryStep {
            state: vec![200.0 + i as f32; 32], // States: 200, 201, 202, 203, 204, 205, 206
            action: FactoredAction::new(ExposureLevel::ShortSmall, OrderType::Market, Urgency::Normal),
            log_prob: -1.0,
            value: 0.5,
            reward: 1.0,
            done: i == 6, // Last step done
        });
    }

    let total_steps = 5 + 7;
    let advantages = vec![0.1; total_steps];
    let returns = vec![0.5; total_steps];

    let batch = TrajectoryBatch::from_trajectories(
        vec![episode1, episode2],
        advantages,
        returns
    );

    let sequences = batch.to_sequence_ranges(8);

    // Verify: Episode 1 states (100-104) never mixed with Episode 2 states (200-206)
    for seq in &sequences {
        let first_state_value = batch.states[seq.start][0];

        // Check that all states in this sequence are from the same episode
        for idx in seq.start..seq.end {
            let state_value = batch.states[idx][0];

            if first_state_value >= 100.0 && first_state_value < 200.0 {
                // Sequence starts in episode 1
                assert!(
                    state_value >= 100.0 && state_value < 200.0,
                    "Sequence starting in episode 1 (state {}) contains episode 2 state ({})",
                    first_state_value, state_value
                );
            } else {
                // Sequence starts in episode 2
                assert!(
                    state_value >= 200.0,
                    "Sequence starting in episode 2 (state {}) contains episode 1 state ({})",
                    first_state_value, state_value
                );
            }
        }
    }
}

#[test]
fn test_varying_episode_lengths_with_small_sequences() {
    // Test edge case: sequence_length > some episodes but < others
    let episode1 = create_trajectory(3, 32);   // Shorter than seq_len
    let episode2 = create_trajectory(20, 32);  // Longer than seq_len
    let episode3 = create_trajectory(5, 32);   // Between

    let total_steps = 3 + 20 + 5;
    let advantages = vec![0.1; total_steps];
    let returns = vec![0.5; total_steps];

    let batch = TrajectoryBatch::from_trajectories(
        vec![episode1, episode2, episode3],
        advantages,
        returns
    );

    let sequences = batch.to_sequence_ranges(8);

    // Verify: Each episode is properly segmented
    // Episode 1 (3 steps): 1 sequence of length 3
    // Episode 2 (20 steps): 3 sequences (8 + 8 + 4)
    // Episode 3 (5 steps): 1 sequence of length 5
    // Total: 5 sequences

    assert_eq!(
        sequences.len(), 5,
        "Expected 5 sequences (1+3+1), got {}",
        sequences.len()
    );

    // Verify no sequence crosses episode boundaries
    for seq in &sequences {
        let done_count = (seq.start..seq.end)
            .filter(|&i| batch.dones[i])
            .count();
        assert!(
            done_count <= 1,
            "Sequence crosses episode boundary (has {} done flags)",
            done_count
        );
    }
}

#[test]
fn test_action_continuity_within_sequences() {
    // Create episodes with different action patterns
    let mut episode1 = Trajectory::new();
    for i in 0..5 {
        episode1.add_step(TrajectoryStep {
            state: vec![0.0; 32],
            action: FactoredAction::new(ExposureLevel::LongFull, OrderType::Market, Urgency::Normal), // All Buy
            log_prob: -1.0,
            value: 0.5,
            reward: 1.0,
            done: i == 4,
        });
    }

    let mut episode2 = Trajectory::new();
    for i in 0..7 {
        episode2.add_step(TrajectoryStep {
            state: vec![0.0; 32],
            action: FactoredAction::new(ExposureLevel::ShortSmall, OrderType::Market, Urgency::Normal), // All Sell
            log_prob: -1.0,
            value: 0.5,
            reward: 1.0,
            done: i == 6,
        });
    }

    let total_steps = 5 + 7;
    let advantages = vec![0.1; total_steps];
    let returns = vec![0.5; total_steps];

    let batch = TrajectoryBatch::from_trajectories(
        vec![episode1, episode2],
        advantages,
        returns
    );

    let sequences = batch.to_sequence_ranges(8);

    // Verify: Actions within each sequence are consistent
    for seq in &sequences {
        if seq.start >= seq.end {
            continue;
        }

        let first_action = batch.actions[seq.start];
        let all_same_action = (seq.start..seq.end)
            .all(|i| batch.actions[i] == first_action);

        // All actions should be the same (Buy or Sell, not mixed)
        assert!(
            all_same_action,
            "Sequence contains mixed actions from different episodes: {:?}",
            (seq.start..seq.end).map(|i| batch.actions[i]).collect::<Vec<_>>()
        );
    }
}

#[test]
fn test_sequence_actual_length_correctness() {
    // Test that actual_length correctly reflects sequence boundaries
    let episode1 = create_trajectory(5, 32);
    let episode2 = create_trajectory(17, 32);

    let total_steps = 5 + 17;
    let advantages = vec![0.1; total_steps];
    let returns = vec![0.5; total_steps];

    let batch = TrajectoryBatch::from_trajectories(
        vec![episode1, episode2],
        advantages,
        returns
    );

    let sequences = batch.to_sequence_ranges(8);

    // Verify: actual_length matches range span (end - start)
    for seq in &sequences {
        let range_len = seq.end - seq.start;
        assert_eq!(
            range_len, seq.actual_length,
            "Mismatch: range span={}, actual_length={}",
            range_len, seq.actual_length
        );

        // Verify the range doesn't exceed batch bounds
        assert!(
            seq.end <= batch.total_steps(),
            "Sequence end {} exceeds batch total_steps {}",
            seq.end, batch.total_steps()
        );

        // Verify all referenced fields are accessible
        for i in seq.start..seq.end {
            assert!(i < batch.states.len(), "State index {} out of bounds", i);
            assert!(i < batch.actions.len(), "Action index {} out of bounds", i);
            assert!(i < batch.log_probs.len(), "Log prob index {} out of bounds", i);
            assert!(i < batch.values.len(), "Value index {} out of bounds", i);
            assert!(i < batch.rewards.len(), "Reward index {} out of bounds", i);
            assert!(i < batch.dones.len(), "Done index {} out of bounds", i);
            assert!(i < batch.advantages.len(), "Advantage index {} out of bounds", i);
            assert!(i < batch.returns.len(), "Return index {} out of bounds", i);
        }
    }
}