//! M3.7.7 integration tests: failure signature extraction + normalisation
//!
//! Verifies that:
//! 1. Same failure from different runs produces identical hash
//! 2. Different failures produce different hashes
//! 3. Normalisation strips volatile data (timestamps, paths, SHAs)
//! 4. Cascading failures pick the root error
//! 5. Unknown tools still produce signatures
//! 6. No model calls are made
//! 7. Extraction is fast (< 50ms for 50KB logs)
//! 8. Tool is part of the signature identity
//! 9. `mem sig explain` names the rule

use mem_core::lesson;
use std::fs;
use std::path::Path;
use std::time::Instant;

fn load_fixture(name: &str) -> String {
    let path = format!("fixtures/failures/{}.txt", name);
    fs::read_to_string(&path).expect(&format!("Failed to load fixture: {}", path))
}

#[test]
fn a1_same_failure_same_hash() {
    // For each tool, two runs of the same failure should produce identical sig_sha
    let tools_and_fixtures = vec![
        ("npm", "npm-run-a", "npm-run-b"),
        ("cargo", "cargo-run-a", "cargo-run-b"),
        ("kubectl", "kubectl-apply-a", "kubectl-apply-b"),
    ];

    for (tool, fixture_a, fixture_b) in tools_and_fixtures {
        let log_a = load_fixture(fixture_a);
        let log_b = load_fixture(fixture_b);

        let sig_a = lesson::extract(tool, &log_a)
            .expect(&format!("Failed to extract signature from {}", fixture_a));
        let sig_b = lesson::extract(tool, &log_b)
            .expect(&format!("Failed to extract signature from {}", fixture_b));

        assert_eq!(
            sig_a.sig_sha, sig_b.sig_sha,
            "Same failure ({}) from different runs should have identical hash. a={}, b={}",
            tool, sig_a.sig_sha, sig_b.sig_sha
        );
    }
}

#[test]
fn a2_different_failure_different_hash() {
    // Different failures from the same tool should produce different hashes
    let tools_and_fixtures = vec![
        ("npm", "npm-run-a", "npm-different"),
        ("cargo", "cargo-run-a", "cargo-different"),
        ("kubectl", "kubectl-apply-a", "kubectl-different"),
    ];

    for (tool, fixture_same, fixture_diff) in tools_and_fixtures {
        let log_same = load_fixture(fixture_same);
        let log_diff = load_fixture(fixture_diff);

        let sig_same = lesson::extract(tool, &log_same)
            .expect(&format!("Failed to extract signature from {}", fixture_same));
        let sig_diff = lesson::extract(tool, &log_diff)
            .expect(&format!("Failed to extract signature from {}", fixture_diff));

        assert_ne!(
            sig_same.sig_sha, sig_diff.sig_sha,
            "Different failures ({}) should have different hashes",
            tool
        );
    }
}

#[test]
fn a3_normalisation_removes_volatiles() {
    // The normalised form should not contain timestamps, paths, SHAs, line numbers
    let log = load_fixture("npm-run-a");
    let sig = lesson::extract("npm", &log).expect("Failed to extract signature");

    // These patterns should NOT appear in the normalised form
    let patterns = vec![
        (r"2026-08-\d{2}T\d{2}:\d{2}:\d{2}", "ISO timestamp"),
        (r"/home/runner/work", "workspace path"),
        (r"\d{7,40}", "git SHA"),
        (r":\d+:\d+", "line:col"),
    ];

    for (pattern, name) in patterns {
        let re = regex::Regex::new(pattern).unwrap();
        if re.is_match(&sig.normalised) {
            panic!(
                "Normalised signature should not contain {} but found in: {}",
                name, sig.normalised
            );
        }
    }
}

#[test]
fn a4_cascade_picks_first() {
    // When multiple error lines exist, pick the root (first), not the consequence
    let log = r#"error: some root cause
error: consequence of root cause
error: further consequence

Error summary
"#;

    let sig = lesson::extract("cargo", log).expect("Failed to extract signature");
    assert!(
        sig.raw.contains("root cause"),
        "Should pick first error, not consequence"
    );
}

#[test]
fn a5_unknown_tool_fallback() {
    // An unrecognised tool should still produce a signature
    let log = load_fixture("npm-run-a");
    let sig = lesson::extract("unknown-tool", &log).expect("Failed to extract signature for unknown tool");

    // Should have a fallback rule
    assert_eq!(sig.tool, "unknown-tool");
    assert!(!sig.normalised.is_empty(), "Should produce normalised form for unknown tool");
}

#[test]
fn a6_no_model_calls() {
    // Extraction should work with no HTTP requests to embedding/LLM services
    // (This test passes if extraction succeeds without panicking)
    let fixtures = vec!["npm-run-a", "npm-different", "cargo-run-a", "kubectl-apply-a"];

    for fixture in fixtures {
        let log = load_fixture(fixture);
        let tool = fixture.split('-').next().unwrap();
        let sig = lesson::extract(tool, &log);
        assert!(sig.is_some(), "Extraction should succeed for {}", fixture);
    }
}

#[test]
fn a7_latency_under_50ms() {
    // Extraction on a 50KB log should complete in under 50ms
    // Create a 50KB synthetic log
    let base_log = load_fixture("npm-run-a");
    let mut large_log = base_log.clone();
    while large_log.len() < 50_000 {
        large_log.push_str(&base_log);
    }
    large_log.truncate(50_000);

    let start = Instant::now();
    let _sig = lesson::extract("npm", &large_log).expect("Failed to extract from 50KB log");
    let elapsed = start.elapsed();

    assert!(
        elapsed.as_millis() < 50,
        "Extraction should complete in < 50ms, took {}ms",
        elapsed.as_millis()
    );
}

#[test]
fn a8_tool_in_identity() {
    // The same normalised text under two different tools should hash differently
    let log = r#"error: connection refused
Error: failed to connect
"#;

    let sig_npm = lesson::extract("npm", log).expect("Failed npm extraction");
    let sig_cargo = lesson::extract("cargo", log).expect("Failed cargo extraction");

    assert_ne!(
        sig_npm.sig_sha, sig_cargo.sig_sha,
        "Same error text under different tools should produce different hashes"
    );
}

#[test]
fn a9_explain_output() {
    // Verify that extract() returns the rule name
    let fixtures = vec![
        ("npm", "npm-run-a"),
        ("cargo", "cargo-run-a"),
        ("kubectl", "kubectl-apply-a"),
    ];

    for (tool, fixture) in fixtures {
        let log = load_fixture(fixture);
        let sig = lesson::extract(tool, &log).expect(&format!("Failed to extract {}", fixture));
        
        // Rule should be set (not empty or "unknown")
        assert!(!sig.rule.is_empty(), "Rule should be set for {}", tool);
        assert_ne!(sig.rule, "unknown", "Rule should be specific for {}", tool);
        
        // Tool should be in rule (e.g., "npm_error_line")
        let rule_lower = sig.rule.to_lowercase();
        let tool_lower = tool.to_lowercase();
        assert!(
            rule_lower.contains(&tool_lower) || rule_lower == "fallback",
            "Rule should mention tool {} or be fallback, got: {}",
            tool, sig.rule
        );
    }
}