//! Existing Generator rejection/rebuild path for a real pre-fix checkpoint.
use super::*;
use crate::engine::{Generator, metal::Executor};
use crate::settings::{
    GenerationPreferences, RuntimePreferences, SpeculativePreferences, effective_settings,
};
use std::sync::Arc;

#[test]
#[ignore = "installed model and actual pre-fix checkpoint; external memory guard required"]
fn issue106_product_discards_old_checkpoint_and_recovers_cold() {
    let root = std::path::PathBuf::from(std::env::var_os("DS4_QWEN38_ARTIFACTS").unwrap());
    let old = std::path::PathBuf::from(std::env::var_os("DS4_ISSUE106_BAD_CHECKPOINT").unwrap());
    let directory =
        std::path::PathBuf::from(std::env::var_os("DS4_ISSUE106_DIR").unwrap()).join("product");
    std::fs::create_dir_all(&directory).unwrap();
    let effective = effective_settings(
        crate::model::ModelChoice::Qwen38FlashNext,
        &GenerationPreferences {
            context_tokens: 4096,
            max_generated_tokens: 1,
            temperature: Some(0.6),
            ..Default::default()
        },
        &RuntimePreferences {
            speculative: SpeculativePreferences {
                glm_mtp: true,
                ..Default::default()
            },
            ..Default::default()
        },
        root.parent().unwrap(),
    )
    .unwrap();
    let mut settings = effective.turn;
    settings.seed = Some(0);
    settings.kv_cache.min_tokens = 0;
    let mut generator = Generator::open(
        &effective.engine,
        Arc::new(Metrics::new(&directory.join("metrics"))),
    )
    .unwrap();
    let path = directory.join("old.bin");
    std::fs::copy(&old, &path).unwrap();
    let selection = generator.select_checkpoint(&path, |_| true).unwrap();
    assert!(!selection.found && selection.incompatible);
    assert!(!path.exists());
    let Executor::QwenMtplx(owner) = &mut generator.executor else {
        unreachable!()
    };
    assert!(owner.live.current.is_none() && owner.live.prefix.is_none());
    let messages = [ChatTurn {
        user: true,
        tool: false,
        system: false,
        skip_previous_eos: false,
        reasoning: None,
        reasoning_complete: true,
        content: "Say hello.".into(),
    }];
    let mut states = Vec::new();
    for target in [&path, &directory.join("fresh.bin")] {
        let out = generator
            .generate(
                target,
                None,
                &messages,
                &settings,
                &AtomicBool::new(false),
                |_, _| {},
                |_, _, _| {},
                |_| {},
            )
            .unwrap();
        assert_eq!(out.cached_tokens, 0);
        assert_eq!(&std::fs::read(target).unwrap()[..8], b"QWMTKV02");
        let Executor::QwenMtplx(owner) = &mut generator.executor else {
            unreachable!()
        };
        let saved = owner.live.current.as_ref().unwrap();
        let mut hashes = Vec::new();
        let payload = saved
            .encode_payload(
                256,
                &owner.execution.streams,
                owner.execution.stream,
                |_, bytes| {
                    hashes.push(crate::engine::metal::qwen_mtplx_tests::hex_digest(&bytes));
                    Ok(())
                },
                || false,
            )
            .unwrap();
        states.push(serde_json::json!({"tokens":saved.token_ids,"payload":payload,"hashes":hashes,"text":out.message.content,"reasoning":out.message.reasoning}));
    }
    assert_eq!(states[0], states[1]);
    println!(
        "{}",
        serde_json::json!({"case":"product_checkpoint_recovery","old_removed":true,"cold_tokens":0,"new_magic":"QWMTKV02","fresh_state_equal":true})
    );
}