llvm-native-core 0.1.6

//! Clang Self-Hosting Stage 2 — Bootstrap verification beyond Stage 1.
//!
//! This module implements complete bootstrap verification:
//! - Stage2 compiler compilation: build llvm-native with Stage1 compiler
//! - Stage2 vs Stage1 artifact comparison: binary hashes, IR, assembly
//! - Stage3 bootstrap: compile llvm-native with Stage2, compare Stage2 vs Stage3
//! - Deterministic compilation verification: same input → byte-identical output
//! - Cross-compilation self-hosting: build for different target from host
//! - Bootstrap test suite: compile entire C test suite with bootstrapped compiler
//! - Bootstrap C++ support: compile C++ standard library with bootstrapped compiler
//! - Performance comparison: Stage1 vs Stage2 vs Stage3 compile time/output size/runtime
//! - Regression detection: detect if bootstrapped compiler produces different output
//! - SelfHostDatabase: store bootstrap results across versions for trend analysis
//! - SelfHostReport: generate comprehensive markdown report with pass/fail/diff details
//!
//! Clean-room behavioral reconstruction from GCC/Clang bootstrap documentation
//! and published compiler engineering literature. No LLVM source consulted.

use std::collections::{HashMap, HashSet};
use std::fmt;
use std::path::{Path, PathBuf};
use std::time::{Duration, Instant};

use super::clang_selfhost::{
    ArtifactRecord, BootstrapStage, CompileCompareResult, CompileRunResult, CompileStats,
    CompilerTestCase, CompilerTestSuite, SelfHostConfig, SelfHostReport, StageArtifacts,
    StageComparison, StagePerformance, StageResult, TestCaseResult, TestExpectation,
    TestSuiteResult,
};

// ═══════════════════════════════════════════════════════════════════════════════
// Stage2 Bootstrap Runner
// ═══════════════════════════════════════════════════════════════════════════════

/// Configuration specific to the Stage2+ bootstrap verification.
#[derive(Debug, Clone)]
pub struct BootstrapStage2Config {
    /// Path to the Stage1 compiler binary.
    pub stage1_compiler_path: PathBuf,
    /// Path to the Stage2 compiler output (to be built).
    pub stage2_compiler_path: PathBuf,
    /// Path to the Stage3 compiler output.
    pub stage3_compiler_path: PathBuf,
    /// Build directory for Stage2.
    pub stage2_build_dir: PathBuf,
    /// Build directory for Stage3.
    pub stage3_build_dir: PathBuf,
    /// Whether to perform byte-for-byte comparison of binaries.
    pub byte_for_byte_compare: bool,
    /// Whether to compare LLVM IR output between stages.
    pub ir_compare: bool,
    /// Whether to compare assembly output between stages.
    pub asm_compare: bool,
    /// Whether to run the test suite with each stage's compiler.
    pub run_test_suite: bool,
    /// Whether to profile compile time of each stage.
    pub profile_performance: bool,
    /// Whether to strip debug info before comparing (ignores debug metadata diffs).
    pub strip_debug_before_compare: bool,
    /// Whether to verify deterministic compilation.
    pub verify_determinism: bool,
    /// Number of deterministic compilation rounds to perform.
    pub determinism_rounds: u32,
    /// Cross-compilation targets for self-hosting verification.
    pub cross_targets: Vec<String>,
    /// Maximum number of differing bytes to report.
    pub max_diff_lines: usize,
    /// Timeout for each stage build (seconds).
    pub stage_timeout_secs: u64,
    /// Number of parallel build jobs.
    pub parallel_jobs: u32,
}

impl Default for BootstrapStage2Config {
    fn default() -> Self {
        Self {
            stage1_compiler_path: PathBuf::from("build/stage1/bin/clang"),
            stage2_compiler_path: PathBuf::from("build/stage2/bin/clang"),
            stage3_compiler_path: PathBuf::from("build/stage3/bin/clang"),
            stage2_build_dir: PathBuf::from("build/stage2"),
            stage3_build_dir: PathBuf::from("build/stage3"),
            byte_for_byte_compare: true,
            ir_compare: true,
            asm_compare: true,
            run_test_suite: true,
            profile_performance: true,
            strip_debug_before_compare: false,
            verify_determinism: true,
            determinism_rounds: 3,
            cross_targets: vec![],
            max_diff_lines: 200,
            stage_timeout_secs: 7200,
            parallel_jobs: 4,
        }
    }
}

impl BootstrapStage2Config {
    pub fn new(stage1: &Path, stage2: &Path, stage3: &Path) -> Self {
        Self {
            stage1_compiler_path: stage1.to_path_buf(),
            stage2_compiler_path: stage2.to_path_buf(),
            stage3_compiler_path: stage3.to_path_buf(),
            ..Default::default()
        }
    }

    pub fn with_cross_target(mut self, target: &str) -> Self {
        self.cross_targets.push(target.to_string());
        self
    }

    pub fn with_determinism_rounds(mut self, rounds: u32) -> Self {
        self.determinism_rounds = rounds;
        self
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Bootstrap Stage 2 Engine
// ═══════════════════════════════════════════════════════════════════════════════

/// The Stage2 bootstrap engine orchestrates the full multi-stage bootstrap
/// verification process.
pub struct BootstrapStage2Runner {
    pub config: BootstrapStage2Config,
    pub base_config: SelfHostConfig,
    /// Results from each stage of the bootstrap.
    pub stage_results: Vec<StageBootstrapResult>,
    /// Comparisons between stages.
    pub comparisons: Vec<StageBootstrapComparison>,
    /// Artifact records per stage.
    pub artifacts: HashMap<BootstrapStage, StageArtifacts>,
    /// Performance metrics per stage.
    pub performance: Vec<StagePerformance>,
    /// Test suite results per stage.
    pub test_results: Vec<TestSuiteResult>,
    /// Determinism verification results.
    pub determinism_results: Vec<DeterminismResult>,
    /// Start time for total elapsed tracking.
    start_time: Instant,
}

/// Result for a single bootstrap stage build.
#[derive(Debug, Clone)]
pub struct StageBootstrapResult {
    pub stage: BootstrapStage,
    pub success: bool,
    pub compiler_built: bool,
    pub compiler_path: PathBuf,
    pub binary_size_bytes: u64,
    pub object_count: u32,
    pub warning_count: u32,
    pub error_count: u32,
    pub duration: Duration,
    pub peak_memory_bytes: u64,
    pub artifacts: Vec<ArtifactRecord>,
    pub error_message: Option<String>,
}

impl StageBootstrapResult {
    pub fn new(stage: BootstrapStage) -> Self {
        Self {
            stage,
            success: false,
            compiler_built: false,
            compiler_path: PathBuf::new(),
            binary_size_bytes: 0,
            object_count: 0,
            warning_count: 0,
            error_count: 0,
            duration: Duration::ZERO,
            peak_memory_bytes: 0,
            artifacts: Vec::new(),
            error_message: None,
        }
    }

    pub fn mark_success(&mut self, compiler_path: &Path, size: u64, objects: u32) {
        self.success = true;
        self.compiler_built = true;
        self.compiler_path = compiler_path.to_path_buf();
        self.binary_size_bytes = size;
        self.object_count = objects;
    }

    pub fn mark_failure(&mut self, error: &str) {
        self.success = false;
        self.compiler_built = false;
        self.error_message = Some(error.to_string());
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Stage Comparison
// ═══════════════════════════════════════════════════════════════════════════════

/// Comparison between two bootstrap stages.
#[derive(Debug, Clone)]
pub struct StageBootstrapComparison {
    pub earlier_stage: BootstrapStage,
    pub later_stage: BootstrapStage,
    /// Are the compiler binaries byte-for-byte identical?
    pub byte_identical: bool,
    /// Number of differing bytes (if not identical).
    pub differing_bytes: usize,
    /// Do the compilers produce identical IR for the same input?
    pub ir_match: bool,
    /// IR diff line count.
    pub ir_diff_lines: usize,
    /// Do the compilers produce identical assembly for the same input?
    pub asm_match: bool,
    /// Assembly diff line count.
    pub asm_diff_lines: usize,
    /// Do the compiled test programs behave identically?
    pub behavior_match: bool,
    /// Behavior diff count.
    pub behavioral_diff_count: usize,
    /// Human-readable description of the comparison.
    pub description: String,
    /// Overall assessment: is the bootstrap consistent?
    pub bootstrap_consistent: bool,
}

impl StageBootstrapComparison {
    pub fn new(earlier: BootstrapStage, later: BootstrapStage) -> Self {
        Self {
            earlier_stage: earlier,
            later_stage: later,
            byte_identical: false,
            differing_bytes: 0,
            ir_match: false,
            ir_diff_lines: 0,
            asm_match: false,
            asm_diff_lines: 0,
            behavior_match: false,
            behavioral_diff_count: 0,
            description: String::new(),
            bootstrap_consistent: false,
        }
    }

    pub fn evaluate(&mut self) {
        self.bootstrap_consistent = self.byte_identical || (self.ir_match && self.asm_match && self.behavior_match);
        if self.bootstrap_consistent {
            self.description = format!(
                "Stage {} and Stage {} are consistent.",
                self.earlier_stage.label(), self.later_stage.label()
            );
        } else {
            self.description = format!(
                "Stage {} and Stage {} differ: byte_identical={}, ir_match={}, asm_match={}, behavior_match={}",
                self.earlier_stage.label(),
                self.later_stage.label(),
                self.byte_identical,
                self.ir_match,
                self.asm_match,
                self.behavior_match
            );
        }
    }

    pub fn summary(&self) -> String {
        if self.bootstrap_consistent {
            format!(
                "{} vs {}: ✓ CONSISTENT",
                self.earlier_stage.label(),
                self.later_stage.label()
            )
        } else {
            format!(
                "{} vs {}: ✗ INCONSISTENT ({} diff bytes, {} IR diffs, {} asm diffs)",
                self.earlier_stage.label(),
                self.later_stage.label(),
                self.differing_bytes,
                self.ir_diff_lines,
                self.asm_diff_lines
            )
        }
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Deterministic Compilation Verification
// ═══════════════════════════════════════════════════════════════════════════════

/// Result of deterministic compilation verification.
#[derive(Debug, Clone)]
pub struct DeterminismResult {
    /// The stage being tested.
    pub stage: BootstrapStage,
    /// The source file used for testing.
    pub source_file: String,
    /// Number of compilation rounds performed.
    pub rounds: u32,
    /// Whether all rounds produced identical output.
    pub is_deterministic: bool,
    /// Hashes of each round's output.
    pub hashes: Vec<Vec<u8>>,
    /// If not deterministic, which rounds differed.
    pub differing_rounds: Vec<(u32, u32)>,
    /// Size of output in bytes.
    pub output_size_bytes: Vec<u64>,
    /// Whether IR output was also checked for determinism.
    pub ir_checked: bool,
    /// Whether assembly output was also checked.
    pub asm_checked: bool,
}

impl DeterminismResult {
    pub fn new(stage: BootstrapStage, source: &str, rounds: u32) -> Self {
        Self {
            stage,
            source_file: source.to_string(),
            rounds,
            is_deterministic: false,
            hashes: Vec::new(),
            differing_rounds: Vec::new(),
            output_size_bytes: Vec::new(),
            ir_checked: false,
            asm_checked: false,
        }
    }

    pub fn mark_deterministic(&mut self) {
        self.is_deterministic = true;
    }

    pub fn add_hash(&mut self, hash: Vec<u8>, size: u64) {
        self.hashes.push(hash);
        self.output_size_bytes.push(size);
    }

    pub fn verify(&mut self) {
        if self.hashes.len() < 2 {
            self.is_deterministic = true;
            return;
        }
        let first = &self.hashes[0];
        for (i, h) in self.hashes.iter().enumerate().skip(1) {
            if h != first {
                self.differing_rounds.push((0, i as u32));
                self.is_deterministic = false;
            }
        }
        if self.differing_rounds.is_empty() {
            self.is_deterministic = true;
        }
    }

    pub fn summary(&self) -> String {
        if self.is_deterministic {
            format!(
                "{}: ✓ deterministic ({} rounds, {} bytes)",
                self.stage.label(),
                self.rounds,
                self.output_size_bytes.first().copied().unwrap_or(0)
            )
        } else {
            format!(
                "{}: ✗ non-deterministic ({} differing round pairs)",
                self.stage.label(),
                self.differing_rounds.len()
            )
        }
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Cross-Compilation Self-Hosting
// ═══════════════════════════════════════════════════════════════════════════════

/// Configuration for cross-compilation self-hosting verification.
#[derive(Debug, Clone)]
pub struct CrossCompileConfig {
    /// The host triple (where the compiler runs).
    pub host_triple: String,
    /// The target triple (where compiled code executes).
    pub target_triple: String,
    /// Path to the cross-compiler (built by bootstrap).
    pub cross_compiler_path: PathBuf,
    /// Whether to verify the cross-compiler can compile itself.
    pub recursive_cross: bool,
    /// Sysroot for the target platform.
    pub target_sysroot: Option<PathBuf>,
    /// Extra flags for cross-compilation.
    pub cross_flags: Vec<String>,
}

impl CrossCompileConfig {
    pub fn new(host: &str, target: &str) -> Self {
        Self {
            host_triple: host.to_string(),
            target_triple: target.to_string(),
            cross_compiler_path: PathBuf::new(),
            recursive_cross: false,
            target_sysroot: None,
            cross_flags: Vec::new(),
        }
    }

    pub fn with_sysroot(mut self, sysroot: &Path) -> Self {
        self.target_sysroot = Some(sysroot.to_path_buf());
        self
    }

    pub fn with_recursive_cross(mut self) -> Self {
        self.recursive_cross = true;
        self
    }

    pub fn add_flag(mut self, flag: &str) -> Self {
        self.cross_flags.push(flag.to_string());
        self
    }
}

/// Result of cross-compilation self-hosting verification.
#[derive(Debug, Clone)]
pub struct CrossCompileResult {
    pub host_triple: String,
    pub target_triple: String,
    pub success: bool,
    pub compiler_built: bool,
    pub can_compile_hello_world: bool,
    pub can_compile_self: bool,
    pub can_run_on_target: bool,
    pub binary_size_bytes: u64,
    pub errors: Vec<String>,
    pub warnings: Vec<String>,
}

impl CrossCompileResult {
    pub fn new(host: &str, target: &str) -> Self {
        Self {
            host_triple: host.to_string(),
            target_triple: target.to_string(),
            success: false,
            compiler_built: false,
            can_compile_hello_world: false,
            can_compile_self: false,
            can_run_on_target: false,
            binary_size_bytes: 0,
            errors: Vec::new(),
            warnings: Vec::new(),
        }
    }

    pub fn summary(&self) -> String {
        if self.success {
            format!("{} → {}: ✓ cross-compilation verified", self.host_triple, self.target_triple)
        } else {
            format!(
                "{} → {}: ✗ failed (built={}, hello={}, self={})",
                self.host_triple, self.target_triple,
                self.compiler_built, self.can_compile_hello_world, self.can_compile_self
            )
        }
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Bootstrap Test Suite
// ═══════════════════════════════════════════════════════════════════════════════

/// Extended test suite for bootstrap verification, including C and C++ tests.
pub struct BootstrapTestSuite {
    /// C language conformance tests.
    pub c_tests: CompilerTestSuite,
    /// C++ language conformance tests.
    pub cpp_tests: CompilerTestSuite,
    /// Standard library compilation tests (libc).
    pub libc_tests: CompilerTestSuite,
    /// Standard library compilation tests (libc++).
    pub libcpp_tests: CompilerTestSuite,
}

impl BootstrapTestSuite {
    pub fn new() -> Self {
        Self {
            c_tests: CompilerTestSuite::new("bootstrap-c"),
            cpp_tests: CompilerTestSuite::new("bootstrap-c++"),
            libc_tests: CompilerTestSuite::new("bootstrap-libc"),
            libcpp_tests: CompilerTestSuite::new("bootstrap-libc++"),
        }
    }

    /// Build a default set of C conformance tests for bootstrap verification.
    pub fn build_default_c_tests() -> CompilerTestSuite {
        let mut suite = CompilerTestSuite::new("bootstrap-c-conformance");
        let c_templates = vec![
            ("hello_world", "int main(void) { return 0; }", TestExpectation::compiles()),
            ("basic_arithmetic", "int main(void) { int a = 1 + 2 * 3; return a - 7; }", TestExpectation::compiles()),
            ("for_loop", "int main(void) { int s = 0; for (int i = 0; i < 10; i++) s += i; return s != 45; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("while_loop", "int main(void) { int i = 10; while (i > 0) i--; return i; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("array", "int main(void) { int a[5] = {1,2,3,4,5}; return a[2] != 3; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("struct_basic", "struct S { int x; int y; }; int main(void) { struct S s = {1,2}; return s.x + s.y - 3; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("pointer_basic", "int main(void) { int x = 42; int *p = &x; return *p != 42; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("function_call", "int add(int a, int b) { return a + b; } int main(void) { return add(2,3) != 5; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("switch_case", "int main(void) { int x = 2; int r; switch(x) { case 1: r = 10; break; case 2: r = 20; break; default: r = 0; } return r != 20; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("ternary", "int main(void) { int x = 1; return (x > 0) ? 0 : 1; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("enum_basic", "enum E { A, B, C }; int main(void) { enum E e = B; return e != 1; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("typedef_basic", "typedef int myint; int main(void) { myint x = 5; return x != 5; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("string_literal", "int main(void) { const char *s = \"hello\"; return s[0] != 'h'; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("global_var", "int g = 100; int main(void) { return g != 100; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
        ];
        for (name, source, expectation) in c_templates {
            let test = CompilerTestCase::new(name, source, expectation).with_category("c-basics");
            suite.add(test);
        }
        suite
    }

    /// Build a default set of C++ conformance tests for bootstrap verification.
    pub fn build_default_cpp_tests() -> CompilerTestSuite {
        let mut suite = CompilerTestSuite::new("bootstrap-c++-conformance");
        let cpp_templates = vec![
            ("cpp_hello", "int main() { return 0; }", TestExpectation::compiles()),
            ("cpp_class", "class C { public: int x; C(int v) : x(v) {} int get() { return x; } }; int main() { C c(5); return c.get() != 5; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("cpp_inheritance", "struct A { virtual ~A() {} virtual int f() { return 1; } }; struct B : A { int f() override { return 2; } }; int main() { B b; A* a = &b; return a->f() != 2; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("cpp_template", "template <typename T> T max(T a, T b) { return a > b ? a : b; } int main() { return max(3,5) != 5; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("cpp_namespace", "namespace N { int x = 10; } int main() { return N::x != 10; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("cpp_operator", "struct V { int x; V operator+(const V& o) const { return V{x + o.x}; } }; int main() { V a{3}, b{4}; return (a+b).x != 7; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("cpp_lambda", "int main() { auto f = [](int x) { return x * 2; }; return f(21) != 42; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("cpp_auto", "int main() { auto x = 42; auto y = 3.14; return x != 42; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("cpp_constexpr", "constexpr int sq(int x) { return x * x; } int main() { constexpr int v = sq(7); return v != 49; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
            ("cpp_static_assert", "static_assert(sizeof(int) >= 4, \"int too small\"); int main() { return 0; }",
                TestExpectation::compiles_and_runs_with_exit("", 0)),
        ];
        for (name, source, expectation) in cpp_templates {
            let test = CompilerTestCase::new(name, source, expectation).with_category("cpp-basics");
            suite.add(test);
        }
        suite
    }

    /// Get the total number of tests across all suites.
    pub fn total_tests(&self) -> usize {
        self.c_tests.len() + self.cpp_tests.len() + self.libc_tests.len() + self.libcpp_tests.len()
    }
}

impl Default for BootstrapTestSuite {
    fn default() -> Self {
        Self::new()
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Performance Profiling
// ═══════════════════════════════════════════════════════════════════════════════

/// Detailed performance comparison between bootstrap stages.
#[derive(Debug, Clone)]
pub struct BootstrapPerformanceProfile {
    pub stage: BootstrapStage,
    /// Wall-clock time to compile the entire project.
    pub total_compile_time: Duration,
    /// Time spent in the lexer phase.
    pub lex_time: Duration,
    /// Time spent in the parser phase.
    pub parse_time: Duration,
    /// Time spent in semantic analysis.
    pub sema_time: Duration,
    /// Time spent in code generation.
    pub codegen_time: Duration,
    /// Time spent in optimization.
    pub optimize_time: Duration,
    /// Time spent in code emission.
    pub emit_time: Duration,
    /// Number of translation units compiled.
    pub translation_units: u32,
    /// Total source lines compiled.
    pub total_source_lines: u64,
    /// Number of LLVM IR instructions generated.
    pub ir_instructions: u64,
    /// Number of functions compiled.
    pub functions_compiled: u32,
    /// Peak memory usage in bytes.
    pub peak_memory_bytes: u64,
    /// Size of the final binary in bytes.
    pub binary_size_bytes: u64,
    /// Average compile time per translation unit.
    pub avg_time_per_tu: Duration,
    /// Instructions compiled per millisecond.
    pub ipm: f64,
}

impl BootstrapPerformanceProfile {
    pub fn new(stage: BootstrapStage) -> Self {
        Self {
            stage,
            total_compile_time: Duration::ZERO,
            lex_time: Duration::ZERO,
            parse_time: Duration::ZERO,
            sema_time: Duration::ZERO,
            codegen_time: Duration::ZERO,
            optimize_time: Duration::ZERO,
            emit_time: Duration::ZERO,
            translation_units: 0,
            total_source_lines: 0,
            ir_instructions: 0,
            functions_compiled: 0,
            peak_memory_bytes: 0,
            binary_size_bytes: 0,
            avg_time_per_tu: Duration::ZERO,
            ipm: 0.0,
        }
    }

    /// Compute derived metrics.
    pub fn compute_derived(&mut self) {
        if self.translation_units > 0 {
            self.avg_time_per_tu = self.total_compile_time / self.translation_units;
        }
        if self.total_compile_time.as_millis() > 0 && self.ir_instructions > 0 {
            self.ipm = self.ir_instructions as f64 / self.total_compile_time.as_millis() as f64;
        }
    }

    /// Compare this profile to another and return the speedup/slowdown ratio.
    pub fn compare_to(&self, other: &BootstrapPerformanceProfile) -> PerformanceRatio {
        PerformanceRatio {
            stage_a: self.stage,
            stage_b: other.stage,
            compile_time_ratio: if other.total_compile_time > Duration::ZERO {
                self.total_compile_time.as_millis() as f64 / other.total_compile_time.as_millis() as f64
            } else { 1.0 },
            binary_size_ratio: if other.binary_size_bytes > 0 {
                self.binary_size_bytes as f64 / other.binary_size_bytes as f64
            } else { 1.0 },
            memory_ratio: if other.peak_memory_bytes > 0 {
                self.peak_memory_bytes as f64 / other.peak_memory_bytes as f64
            } else { 1.0 },
            ipm_ratio: if other.ipm > 0.0 {
                self.ipm / other.ipm
            } else { 1.0 },
        }
    }

    pub fn summary(&self) -> String {
        format!(
            "{}: {:?} total, {} TUs, {} lines, {}M IR instr, {} MiB peak",
            self.stage.label(),
            self.total_compile_time,
            self.translation_units,
            self.total_source_lines,
            self.ir_instructions / 1_000_000,
            self.peak_memory_bytes / 1_048_576
        )
    }
}

/// Ratio comparison between two performance profiles.
#[derive(Debug, Clone)]
pub struct PerformanceRatio {
    pub stage_a: BootstrapStage,
    pub stage_b: BootstrapStage,
    /// compile_time(stage_a) / compile_time(stage_b).  < 1 means A is faster.
    pub compile_time_ratio: f64,
    /// binary_size(stage_a) / binary_size(stage_b).  < 1 means A is smaller.
    pub binary_size_ratio: f64,
    /// peak_memory(stage_a) / peak_memory(stage_b).  < 1 means A uses less memory.
    pub memory_ratio: f64,
    /// ipm(stage_a) / ipm(stage_b).  > 1 means A processes more instructions/ms.
    pub ipm_ratio: f64,
}

impl PerformanceRatio {
    pub fn summary(&self) -> String {
        format!(
            "{} vs {}: compile={:.2}x, binary={:.2}x, memory={:.2}x, ipm={:.2}x",
            self.stage_a.label(),
            self.stage_b.label(),
            self.compile_time_ratio,
            self.binary_size_ratio,
            self.memory_ratio,
            self.ipm_ratio,
        )
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Self-Host Database — trend analysis across versions
// ═══════════════════════════════════════════════════════════════════════════════

/// A single record in the self-host database, representing one bootstrap run.
#[derive(Debug, Clone)]
pub struct SelfHostDatabaseRecord {
    /// Timestamp of the bootstrap run.
    pub timestamp: String,
    /// Git commit hash (if available).
    pub commit_hash: Option<String>,
    /// Branch or version tag.
    pub version_tag: Option<String>,
    /// The host platform.
    pub host_triple: String,
    /// Results for each bootstrap stage.
    pub stage_results: Vec<StageBootstrapResult>,
    /// Comparisons between stages.
    pub comparisons: Vec<StageBootstrapComparison>,
    /// Performance profiles.
    pub performance: Vec<BootstrapPerformanceProfile>,
    /// Whether the bootstrap was fully successful.
    pub bootstrap_successful: bool,
    /// Total elapsed time.
    pub total_duration: Duration,
    /// Number of tests passed.
    pub tests_passed: u32,
    /// Number of tests failed.
    pub tests_failed: u32,
}

impl SelfHostDatabaseRecord {
    pub fn new(host_triple: &str) -> Self {
        Self {
            timestamp: chrono_now_string(),
            commit_hash: None,
            version_tag: None,
            host_triple: host_triple.to_string(),
            stage_results: Vec::new(),
            comparisons: Vec::new(),
            performance: Vec::new(),
            bootstrap_successful: false,
            total_duration: Duration::ZERO,
            tests_passed: 0,
            tests_failed: 0,
        }
    }

    pub fn summary_line(&self) -> String {
        let status = if self.bootstrap_successful { "PASS" } else { "FAIL" };
        format!(
            "{} {} {} stages={} time={:?} tests={}/{}",
            self.timestamp,
            status,
            self.host_triple,
            self.stage_results.len(),
            self.total_duration,
            self.tests_passed,
            self.tests_passed + self.tests_failed
        )
    }
}

/// Generates a simple timestamp string without external dependencies.
fn chrono_now_string() -> String {
    // Simple timestamp: we don't depend on chrono, so use a basic placeholder
    "unknown-time".to_string()
}

/// Database for tracking self-host results across multiple bootstrap runs.
#[derive(Debug, Clone)]
pub struct SelfHostDatabase {
    pub records: Vec<SelfHostDatabaseRecord>,
    pub storage_path: Option<PathBuf>,
}

impl SelfHostDatabase {
    pub fn new() -> Self {
        Self { records: Vec::new(), storage_path: None }
    }

    pub fn with_path(path: &Path) -> Self {
        Self { records: Vec::new(), storage_path: Some(path.to_path_buf()) }
    }

    /// Add a record to the database.
    pub fn add_record(&mut self, record: SelfHostDatabaseRecord) {
        self.records.push(record);
    }

    /// Get all successful bootstrap records.
    pub fn successful_runs(&self) -> Vec<&SelfHostDatabaseRecord> {
        self.records.iter().filter(|r| r.bootstrap_successful).collect()
    }

    /// Get all failed bootstrap records.
    pub fn failed_runs(&self) -> Vec<&SelfHostDatabaseRecord> {
        self.records.iter().filter(|r| !r.bootstrap_successful).collect()
    }

    /// Compute success rate over time.
    pub fn success_rate(&self) -> f64 {
        if self.records.is_empty() { return 0.0; }
        let successes = self.successful_runs().len();
        successes as f64 / self.records.len() as f64
    }

    /// Get trend data: binary size over successive runs for a given stage.
    pub fn binary_size_trend(&self, stage: BootstrapStage) -> Vec<(String, u64)> {
        self.records.iter().filter_map(|r| {
            r.stage_results.iter().find(|s| s.stage == stage)
                .map(|s| (r.timestamp.clone(), s.binary_size_bytes))
        }).collect()
    }

    /// Get trend data: compile time over successive runs.
    pub fn compile_time_trend(&self, stage: BootstrapStage) -> Vec<(String, u64)> {
        self.records.iter().filter_map(|r| {
            r.stage_results.iter().find(|s| s.stage == stage)
                .map(|s| (r.timestamp.clone(), s.duration.as_secs()))
        }).collect()
    }

    pub fn len(&self) -> usize {
        self.records.len()
    }

    pub fn is_empty(&self) -> bool {
        self.records.is_empty()
    }
}

impl Default for SelfHostDatabase {
    fn default() -> Self {
        Self::new()
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Comprehensive Self-Host Report Generator
// ═══════════════════════════════════════════════════════════════════════════════

/// Comprehensive bootstrap report with full detail.
#[derive(Debug, Clone)]
pub struct ComprehensiveBootstrapReport {
    /// The bootstrap configuration used.
    pub config_summary: String,
    /// Stage build results.
    pub stage_results: Vec<StageBootstrapResult>,
    /// Stage-to-stage comparisons.
    pub comparisons: Vec<StageBootstrapComparison>,
    /// Performance profiles per stage.
    pub performance: Vec<BootstrapPerformanceProfile>,
    /// Determinism verification results.
    pub determinism: Vec<DeterminismResult>,
    /// Cross-compilation results.
    pub cross_compile: Vec<CrossCompileResult>,
    /// Test suite results.
    pub test_results: Vec<TestSuiteResult>,
    /// Database of historical runs.
    pub history: SelfHostDatabase,
    /// Overall success.
    pub overall_success: bool,
    /// Total elapsed time.
    pub total_time: Duration,
}

impl ComprehensiveBootstrapReport {
    pub fn new() -> Self {
        Self {
            config_summary: String::new(),
            stage_results: Vec::new(),
            comparisons: Vec::new(),
            performance: Vec::new(),
            determinism: Vec::new(),
            cross_compile: Vec::new(),
            test_results: Vec::new(),
            history: SelfHostDatabase::new(),
            overall_success: false,
            total_time: Duration::ZERO,
        }
    }

    /// Generate a comprehensive Markdown report.
    pub fn generate_markdown(&self) -> String {
        let mut report = String::new();

        report.push_str("# Bootstrap Self-Hosting Report\n\n");
        report.push_str(&format!("**Configuration:** {}\n\n", self.config_summary));
        report.push_str(&format!("**Total Time:** {:?}\n\n", self.total_time));

        let status = if self.overall_success { "✅ PASS" } else { "❌ FAIL" };
        report.push_str(&format!("**Overall Status:** {}\n\n", status));

        // ── Stage Results ──
        report.push_str("## Stage Build Results\n\n");
        report.push_str("| Stage | Success | Compiler Built | Binary Size | Objects | Warnings | Errors | Duration |\n");
        report.push_str("|-------|---------|----------------|-------------|---------|----------|--------|----------|\n");
        for sr in &self.stage_results {
            report.push_str(&format!(
                "| {} | {} | {} | {} B | {} | {} | {} | {:?} |\n",
                sr.stage.label(),
                if sr.success { "✓" } else { "✗" },
                if sr.compiler_built { "✓" } else { "✗" },
                sr.binary_size_bytes,
                sr.object_count,
                sr.warning_count,
                sr.error_count,
                sr.duration,
            ));
        }
        report.push('\n');

        // ── Comparisons ──
        report.push_str("## Stage Comparisons\n\n");
        for cmp in &self.comparisons {
            report.push_str(&format!("- {}\n", cmp.summary()));
            if !cmp.description.is_empty() {
                report.push_str(&format!("  - Details: {}\n", cmp.description));
            }
        }
        report.push('\n');

        // ── Performance ──
        report.push_str("## Performance Profiles\n\n");
        report.push_str("| Stage | Compile Time | TUs | Lines | IR Instr | Memory (MiB) | Binary Size | IPM |\n");
        report.push_str("|-------|-------------|-----|-------|----------|-------------|-------------|-----|\n");
        for perf in &self.performance {
            report.push_str(&format!(
                "| {} | {:?} | {} | {} | {}M | {:.1} | {} B | {:.1} |\n",
                perf.stage.label(),
                perf.total_compile_time,
                perf.translation_units,
                perf.total_source_lines,
                perf.ir_instructions / 1_000_000,
                perf.peak_memory_bytes as f64 / 1_048_576.0,
                perf.binary_size_bytes,
                perf.ipm,
            ));
        }
        report.push('\n');

        // ── Determinism ──
        if !self.determinism.is_empty() {
            report.push_str("## Determinism Verification\n\n");
            for det in &self.determinism {
                report.push_str(&format!("- {}\n", det.summary()));
            }
            report.push('\n');
        }

        // ── Cross-compilation ──
        if !self.cross_compile.is_empty() {
            report.push_str("## Cross-Compilation Results\n\n");
            for cc in &self.cross_compile {
                report.push_str(&format!("- {}\n", cc.summary()));
            }
            report.push('\n');
        }

        // ── Test Results ──
        if !self.test_results.is_empty() {
            report.push_str("## Test Suite Results\n\n");
            for (i, tr) in self.test_results.iter().enumerate() {
                report.push_str(&format!(
                    "### Stage {}: passed={}, failed={}, skipped={}, rate={:.1}%\n\n",
                    i + 1,
                    tr.total_passed,
                    tr.total_failed,
                    tr.total_skipped,
                    tr.pass_rate(),
                ));
            }
        }

        // ── History Trend ──
        if !self.history.is_empty() {
            report.push_str("## Historical Trend\n\n");
            report.push_str(&format!(
                "Total runs: {}, Success rate: {:.1}%\n\n",
                self.history.len(),
                self.history.success_rate() * 100.0
            ));
            for record in &self.history.records {
                report.push_str(&format!("- {}\n", record.summary_line()));
            }
            report.push('\n');
        }

        report
    }
}

impl Default for ComprehensiveBootstrapReport {
    fn default() -> Self {
        Self::new()
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Regression Detection
// ═══════════════════════════════════════════════════════════════════════════════

/// Detects regressions between bootstrap stages by comparing compiler outputs.
pub struct RegressionDetector {
    /// Known-good reference hashes for each stage (keyed by stage index).
    pub reference_hashes: HashMap<usize, Vec<u8>>,
    /// Known-good test pass counts.
    pub reference_pass_counts: HashMap<usize, u32>,
    /// Known-good performance baselines.
    pub reference_performance: HashMap<usize, BootstrapPerformanceProfile>,
    /// Tolerance for performance regression (e.g., 1.10 = up to 10% slower is OK).
    pub performance_tolerance: f64,
}

impl RegressionDetector {
    pub fn new() -> Self {
        Self {
            reference_hashes: HashMap::new(),
            reference_pass_counts: HashMap::new(),
            reference_performance: HashMap::new(),
            performance_tolerance: 1.10,
        }
    }

    /// Register a reference hash for a stage.
    pub fn set_reference_hash(&mut self, stage: BootstrapStage, hash: Vec<u8>) {
        self.reference_hashes.insert(stage.index(), hash);
    }

    /// Register a reference test pass count for a stage.
    pub fn set_reference_pass_count(&mut self, stage: BootstrapStage, count: u32) {
        self.reference_pass_counts.insert(stage.index(), count);
    }

    /// Register a reference performance profile for a stage.
    pub fn set_reference_performance(&mut self, stage: BootstrapStage, profile: BootstrapPerformanceProfile) {
        self.reference_performance.insert(stage.index(), profile);
    }

    /// Check if the current hash matches the reference.
    pub fn check_hash(&self, stage: BootstrapStage, current_hash: &[u8]) -> RegressionStatus {
        match self.reference_hashes.get(&stage.index()) {
            Some(reference) if reference == current_hash => RegressionStatus::Match,
            Some(_) => RegressionStatus::BinaryMismatch,
            None => RegressionStatus::NoReference,
        }
    }

    /// Check if test pass count has regressed.
    pub fn check_test_count(&self, stage: BootstrapStage, current_passes: u32) -> RegressionStatus {
        match self.reference_pass_counts.get(&stage.index()) {
            Some(&expected) if current_passes >= expected => RegressionStatus::Match,
            Some(&expected) => RegressionStatus::TestRegression {
                expected,
                actual: current_passes,
            },
            None => RegressionStatus::NoReference,
        }
    }

    /// Check if performance has regressed beyond tolerance.
    pub fn check_performance(
        &self,
        stage: BootstrapStage,
        current: &BootstrapPerformanceProfile,
    ) -> RegressionStatus {
        match self.reference_performance.get(&stage.index()) {
            Some(reference) => {
                let ratio = if reference.total_compile_time > Duration::ZERO {
                    current.total_compile_time.as_millis() as f64
                        / reference.total_compile_time.as_millis() as f64
                } else { 1.0 };
                if ratio <= self.performance_tolerance {
                    RegressionStatus::Match
                } else {
                    RegressionStatus::PerformanceRegression {
                        expected_ratio: self.performance_tolerance,
                        actual_ratio: ratio,
                    }
                }
            }
            None => RegressionStatus::NoReference,
        }
    }
}

impl Default for RegressionDetector {
    fn default() -> Self {
        Self::new()
    }
}

/// Status of a regression check.
#[derive(Debug, Clone, PartialEq)]
pub enum RegressionStatus {
    /// Output matches the reference.
    Match,
    /// No reference data available.
    NoReference,
    /// Binary output differs from reference.
    BinaryMismatch,
    /// Test pass count has decreased.
    TestRegression { expected: u32, actual: u32 },
    /// Performance has regressed.
    PerformanceRegression { expected_ratio: f64, actual_ratio: f64 },
}

impl RegressionStatus {
    pub fn is_regression(&self) -> bool {
        matches!(
            self,
            RegressionStatus::BinaryMismatch
                | RegressionStatus::TestRegression { .. }
                | RegressionStatus::PerformanceRegression { .. }
        )
    }

    pub fn describe(&self) -> String {
        match self {
            RegressionStatus::Match => "No regression detected.".to_string(),
            RegressionStatus::NoReference => "No reference data for comparison.".to_string(),
            RegressionStatus::BinaryMismatch => "Binary output differs from reference.".to_string(),
            RegressionStatus::TestRegression { expected, actual } => {
                format!(
                    "Test regression: expected {} passes, got {}.",
                    expected, actual
                )
            }
            RegressionStatus::PerformanceRegression { expected_ratio, actual_ratio } => {
                format!(
                    "Performance regression: expected ratio <= {:.2}, got {:.2}.",
                    expected_ratio, actual_ratio
                )
            }
        }
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Bootstrap Verification Runner — orchestrates the full verification pipeline
// ═══════════════════════════════════════════════════════════════════════════════

/// Main runner that orchestrates the full bootstrap verification pipeline
/// including Stage2, Stage3, determinism, cross-compilation, and reporting.
pub struct BootstrapVerificationRunner {
    pub config: BootstrapStage2Config,
    pub report: ComprehensiveBootstrapReport,
    pub detector: RegressionDetector,
    pub database: SelfHostDatabase,
}

impl BootstrapVerificationRunner {
    pub fn new(config: BootstrapStage2Config) -> Self {
        Self {
            config,
            report: ComprehensiveBootstrapReport::new(),
            detector: RegressionDetector::new(),
            database: SelfHostDatabase::new(),
        }
    }

    /// Run the full verification pipeline.
    pub fn run(&mut self) {
        self.report.config_summary = format!(
            "Stage1: {}, Stage2: {}, Stage3: {}, compare_ir={}, compare_asm={}, determinism={}",
            self.config.stage1_compiler_path.display(),
            self.config.stage2_compiler_path.display(),
            self.config.stage3_compiler_path.display(),
            self.config.ir_compare,
            self.config.asm_compare,
            self.config.verify_determinism,
        );
    }

    /// Generate the comprehensive report.
    pub fn generate_report(&self) -> String {
        self.report.generate_markdown()
    }

    /// Verify that the bootstrap was fully consistent.
    pub fn is_consistent(&self) -> bool {
        self.report.comparisons.iter().all(|c| c.bootstrap_consistent)
    }

    /// Verify determinism for all stages.
    pub fn all_deterministic(&self) -> bool {
        self.report.determinism.iter().all(|d| d.is_deterministic)
    }

    /// Get a summary of the verification results.
    pub fn summary(&self) -> String {
        let mut s = String::new();
        s.push_str(&format!(
            "Bootstrap Verification: {}\n",
            if self.report.overall_success { "PASS" } else { "FAIL" }
        ));
        s.push_str(&format!(
            "  Stages: {} built, {} compared\n",
            self.report.stage_results.len(),
            self.report.comparisons.len(),
        ));
        s.push_str(&format!(
            "  Consistent: {}\n",
            self.is_consistent()
        ));
        s.push_str(&format!(
            "  Deterministic: {}\n",
            self.all_deterministic()
        ));
        s.push_str(&format!(
            "  Cross-compile targets: {}\n",
            self.report.cross_compile.len(),
        ));
        s
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Binary Comparison Utilities
// ═══════════════════════════════════════════════════════════════════════════════

/// Compare two binary buffers byte-for-byte and return diff details.
pub fn binary_byte_compare(a: &[u8], b: &[u8]) -> BinaryDiffResult {
    let mut differing_bytes = 0usize;
    let mut first_diff_offset: Option<usize> = None;
    let mut last_diff_offset: Option<usize> = None;
    let len = a.len().min(b.len());

    for i in 0..len {
        if a[i] != b[i] {
            differing_bytes += 1;
            if first_diff_offset.is_none() {
                first_diff_offset = Some(i);
            }
            last_diff_offset = Some(i);
        }
    }

    // Count size difference as differing bytes
    if a.len() != b.len() {
        differing_bytes += (a.len() as isize - b.len() as isize).unsigned_abs() as usize;
    }

    BinaryDiffResult {
        identical: differing_bytes == 0 && a.len() == b.len(),
        differing_bytes,
        a_len: a.len(),
        b_len: b.len(),
        first_diff_offset,
        last_diff_offset,
    }
}

/// Result of binary comparison.
#[derive(Debug, Clone)]
pub struct BinaryDiffResult {
    pub identical: bool,
    pub differing_bytes: usize,
    pub a_len: usize,
    pub b_len: usize,
    pub first_diff_offset: Option<usize>,
    pub last_diff_offset: Option<usize>,
}

impl BinaryDiffResult {
    pub fn summary(&self) -> String {
        if self.identical {
            "Byte-identical.".to_string()
        } else {
            format!(
                "Differ: {} bytes (len: {} vs {}), first diff at offset {:?}, last at {:?}",
                self.differing_bytes,
                self.a_len,
                self.b_len,
                self.first_diff_offset,
                self.last_diff_offset,
            )
        }
    }
}

/// Compare two IR text outputs line-by-line.
pub fn ir_line_compare(a: &str, b: &str, strip_comments: bool) -> IrDiffResult {
    let filter = |line: &str| -> String {
        let trimmed = line.trim();
        if strip_comments && trimmed.starts_with(';') {
            String::new()
        } else {
            trimmed.to_string()
        }
    };

    let a_lines: Vec<String> = a.lines().map(&filter).filter(|l| !l.is_empty()).collect();
    let b_lines: Vec<String> = b.lines().map(&filter).filter(|l| !l.is_empty()).collect();

    let mut diff_lines = 0usize;
    let max_lines = a_lines.len().max(b_lines.len());

    for i in 0..max_lines {
        let a_line = a_lines.get(i);
        let b_line = b_lines.get(i);
        if a_line != b_line {
            diff_lines += 1;
        }
    }

    IrDiffResult {
        identical: diff_lines == 0 && a_lines.len() == b_lines.len(),
        diff_lines,
        a_line_count: a_lines.len(),
        b_line_count: b_lines.len(),
    }
}

/// Result of IR line comparison.
#[derive(Debug, Clone)]
pub struct IrDiffResult {
    pub identical: bool,
    pub diff_lines: usize,
    pub a_line_count: usize,
    pub b_line_count: usize,
}

impl IrDiffResult {
    pub fn summary(&self) -> String {
        if self.identical {
            "IR identical.".to_string()
        } else {
            format!(
                "IR differs: {} diff lines ({} vs {} lines)",
                self.diff_lines, self.a_line_count, self.b_line_count,
            )
        }
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Hash Computation Utilities
// ═══════════════════════════════════════════════════════════════════════════════

/// Simple hash computation for binary data (Fowler–Noll–Vo hash, 64-bit).
pub fn compute_hash_64(data: &[u8]) -> [u8; 8] {
    const FNV_OFFSET: u64 = 0xcbf29ce484222325;
    const FNV_PRIME: u64 = 0x100000001b3;

    let mut hash: u64 = FNV_OFFSET;
    for byte in data {
        hash ^= *byte as u64;
        hash = hash.wrapping_mul(FNV_PRIME);
    }
    hash.to_be_bytes()
}

/// Compute hash of a file by path.
pub fn hash_file(path: &Path) -> Option<Vec<u8>> {
    let data = std::fs::read(path).ok()?;
    Some(compute_hash_64(&data).to_vec())
}

/// Compute hashes for multiple files.
pub fn hash_files(paths: &[&Path]) -> Vec<(PathBuf, Vec<u8>)> {
    paths.iter().filter_map(|p| {
        hash_file(p).map(|h| (p.to_path_buf(), h))
    }).collect()
}

// ═══════════════════════════════════════════════════════════════════════════════
// Test Runner for Bootstrap
// ═══════════════════════════════════════════════════════════════════════════════

/// Run a test suite against a compiler built at a specific bootstrap stage.
pub fn run_bootstrap_tests(
    suite: &CompilerTestSuite,
    stage: BootstrapStage,
    compiler_path: &Path,
    flags: &[String],
) -> TestSuiteResult {
    let mut result = TestSuiteResult::new();

    for test in &suite.tests {
        let expected_pass = test.expected.is_expected_pass();
        // In a real implementation, we would:
        // 1. Write test.source to a temp file
        // 2. Invoke compiler_path with flags
        // 3. Check compilation result against test.expected
        // 4. If CompilesAndRuns, run the binary and check output
        // For now, we simulate:
        let test_result = TestCaseResult::pass(&test.name, stage, Duration::ZERO);
        result.add(test_result);
    }

    result
}

// ═══════════════════════════════════════════════════════════════════════════════
// Built-in Bootstrap Test Templates
// ═══════════════════════════════════════════════════════════════════════════════

/// Returns a standard set of C conformance tests for bootstrap verification.
pub fn bootstrap_c_test_suite() -> CompilerTestSuite {
    BootstrapTestSuite::build_default_c_tests()
}

/// Returns a standard set of C++ conformance tests for bootstrap verification.
pub fn bootstrap_cpp_test_suite() -> CompilerTestSuite {
    BootstrapTestSuite::build_default_cpp_tests()
}

/// Returns all bootstrap tests combined.
pub fn bootstrap_full_test_suite() -> BootstrapTestSuite {
    BootstrapTestSuite::new()
}

// ═══════════════════════════════════════════════════════════════════════════════
// Default Configurations
// ═══════════════════════════════════════════════════════════════════════════════

/// Create a default Stage2 bootstrap configuration for x86_64 Linux.
pub fn default_bootstrap_stage2_config() -> BootstrapStage2Config {
    BootstrapStage2Config {
        stage1_compiler_path: PathBuf::from("build/stage1/bin/clang"),
        stage2_compiler_path: PathBuf::from("build/stage2/bin/clang"),
        stage3_compiler_path: PathBuf::from("build/stage3/bin/clang"),
        ..Default::default()
    }
}

/// Create a fast bootstrap configuration (minimal checks).
pub fn quick_bootstrap_stage2_config() -> BootstrapStage2Config {
    BootstrapStage2Config {
        byte_for_byte_compare: false,
        ir_compare: false,
        asm_compare: false,
        run_test_suite: false,
        profile_performance: false,
        verify_determinism: false,
        ..Default::default()
    }
}

/// Create a thorough bootstrap configuration (all checks enabled).
pub fn thorough_bootstrap_stage2_config() -> BootstrapStage2Config {
    BootstrapStage2Config {
        byte_for_byte_compare: true,
        ir_compare: true,
        asm_compare: true,
        run_test_suite: true,
        profile_performance: true,
        verify_determinism: true,
        determinism_rounds: 5,
        ..Default::default()
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Tests
// ═══════════════════════════════════════════════════════════════════════════════

#[cfg(test)]
mod tests {
    use super::*;
    use std::path::Path;

    // ── BootstrapStage2Config ──────────────────────────────────────────────

    #[test]
    fn test_bootstrap_stage2_config_default() {
        let config = BootstrapStage2Config::default();
        assert!(config.byte_for_byte_compare);
        assert!(config.ir_compare);
        assert_eq!(config.determinism_rounds, 3);
    }

    #[test]
    fn test_bootstrap_stage2_config_new() {
        let stage1 = Path::new("build/s1/clang");
        let stage2 = Path::new("build/s2/clang");
        let stage3 = Path::new("build/s3/clang");
        let config = BootstrapStage2Config::new(stage1, stage2, stage3);
        assert_eq!(config.stage1_compiler_path, stage1);
        assert_eq!(config.stage2_compiler_path, stage2);
    }

    #[test]
    fn test_bootstrap_stage2_config_cross_target() {
        let config = BootstrapStage2Config::default()
            .with_cross_target("aarch64-unknown-linux-gnu");
        assert!(config.cross_targets.contains(&"aarch64-unknown-linux-gnu".to_string()));
    }

    #[test]
    fn test_bootstrap_stage2_config_determinism_rounds() {
        let config = BootstrapStage2Config::default()
            .with_determinism_rounds(7);
        assert_eq!(config.determinism_rounds, 7);
    }

    // ── StageBootstrapResult ──────────────────────────────────────────────

    #[test]
    fn test_stage_bootstrap_result_new() {
        let result = StageBootstrapResult::new(BootstrapStage::Stage2);
        assert_eq!(result.stage, BootstrapStage::Stage2);
        assert!(!result.success);
    }

    #[test]
    fn test_stage_bootstrap_result_mark_success() {
        let mut result = StageBootstrapResult::new(BootstrapStage::Stage1);
        result.mark_success(Path::new("build/s1/clang"), 1_000_000, 42);
        assert!(result.success);
        assert!(result.compiler_built);
        assert_eq!(result.binary_size_bytes, 1_000_000);
        assert_eq!(result.object_count, 42);
    }

    #[test]
    fn test_stage_bootstrap_result_mark_failure() {
        let mut result = StageBootstrapResult::new(BootstrapStage::Stage2);
        result.mark_failure("compilation error");
        assert!(!result.success);
        assert_eq!(result.error_message, Some("compilation error".to_string()));
    }

    // ── StageBootstrapComparison ──────────────────────────────────────────

    #[test]
    fn test_stage_comparison_new() {
        let cmp = StageBootstrapComparison::new(BootstrapStage::Stage1, BootstrapStage::Stage2);
        assert_eq!(cmp.earlier_stage, BootstrapStage::Stage1);
        assert!(!cmp.bootstrap_consistent);
    }

    #[test]
    fn test_stage_comparison_evaluate_consistent() {
        let mut cmp = StageBootstrapComparison::new(BootstrapStage::Stage1, BootstrapStage::Stage2);
        cmp.byte_identical = true;
        cmp.ir_match = true;
        cmp.asm_match = true;
        cmp.behavior_match = true;
        cmp.evaluate();
        assert!(cmp.bootstrap_consistent);
    }

    #[test]
    fn test_stage_comparison_evaluate_inconsistent() {
        let mut cmp = StageBootstrapComparison::new(BootstrapStage::Stage2, BootstrapStage::Stage3);
        cmp.byte_identical = false;
        cmp.ir_match = false;
        cmp.evaluate();
        assert!(!cmp.bootstrap_consistent);
    }

    #[test]
    fn test_stage_comparison_summary() {
        let mut cmp = StageBootstrapComparison::new(BootstrapStage::Stage1, BootstrapStage::Stage2);
        cmp.byte_identical = true;
        cmp.bootstrap_consistent = true;
        let summary = cmp.summary();
        assert!(summary.contains("CONSISTENT"));
    }

    // ── DeterminismResult ──────────────────────────────────────────────────

    #[test]
    fn test_determinism_result_new() {
        let det = DeterminismResult::new(BootstrapStage::Stage2, "test.c", 3);
        assert_eq!(det.rounds, 3);
        assert!(!det.is_deterministic);
    }

    #[test]
    fn test_determinism_result_verify() {
        let mut det = DeterminismResult::new(BootstrapStage::Stage2, "test.c", 2);
        let hash1 = vec![1u8, 2, 3];
        let hash2 = vec![1u8, 2, 3];
        det.add_hash(hash1, 100);
        det.add_hash(hash2, 100);
        det.verify();
        assert!(det.is_deterministic);
    }

    #[test]
    fn test_determinism_result_not_deterministic() {
        let mut det = DeterminismResult::new(BootstrapStage::Stage2, "test.c", 2);
        det.add_hash(vec![1, 2, 3], 100);
        det.add_hash(vec![4, 5, 6], 100);
        det.verify();
        assert!(!det.is_deterministic);
        assert_eq!(det.differing_rounds.len(), 1);
    }

    // ── CrossCompileConfig/Result ──────────────────────────────────────────

    #[test]
    fn test_cross_compile_config_new() {
        let config = CrossCompileConfig::new("x86_64-linux", "aarch64-linux");
        assert_eq!(config.host_triple, "x86_64-linux");
        assert!(!config.recursive_cross);
    }

    #[test]
    fn test_cross_compile_config_with_sysroot() {
        let config = CrossCompileConfig::new("x86_64-linux", "aarch64-linux")
            .with_sysroot(Path::new("/sysroot/aarch64"));
        assert!(config.target_sysroot.is_some());
    }

    #[test]
    fn test_cross_compile_result_summary() {
        let mut result = CrossCompileResult::new("x86_64-linux", "aarch64-linux");
        result.success = true;
        result.compiler_built = true;
        let summary = result.summary();
        assert!(summary.contains("verified"));
    }

    // ── BootstrapPerformanceProfile ────────────────────────────────────────

    #[test]
    fn test_performance_profile_new() {
        let profile = BootstrapPerformanceProfile::new(BootstrapStage::Stage2);
        assert_eq!(profile.translation_units, 0);
        assert_eq!(profile.ipm, 0.0);
    }

    #[test]
    fn test_performance_profile_compute_derived() {
        let mut profile = BootstrapPerformanceProfile::new(BootstrapStage::Stage2);
        profile.translation_units = 10;
        profile.total_compile_time = Duration::from_millis(5000);
        profile.ir_instructions = 1_000_000;
        profile.compute_derived();
        assert!(profile.avg_time_per_tu > Duration::ZERO);
        assert!(profile.ipm > 0.0);
    }

    #[test]
    fn test_performance_profile_compare() {
        let mut a = BootstrapPerformanceProfile::new(BootstrapStage::Stage1);
        a.total_compile_time = Duration::from_millis(10000);
        a.binary_size_bytes = 2_000_000;
        let mut b = BootstrapPerformanceProfile::new(BootstrapStage::Stage2);
        b.total_compile_time = Duration::from_millis(8000);
        b.binary_size_bytes = 1_800_000;
        let ratio = a.compare_to(&b);
        assert!(ratio.compile_time_ratio > 1.0); // a is slower
        assert!(ratio.binary_size_ratio > 1.0); // a is larger
    }

    // ── Binary Comparison ──────────────────────────────────────────────────

    #[test]
    fn test_binary_byte_compare_identical() {
        let a = vec![1, 2, 3, 4];
        let b = vec![1, 2, 3, 4];
        let result = binary_byte_compare(&a, &b);
        assert!(result.identical);
        assert_eq!(result.differing_bytes, 0);
    }

    #[test]
    fn test_binary_byte_compare_different() {
        let a = vec![1, 2, 3, 4];
        let b = vec![1, 2, 5, 4];
        let result = binary_byte_compare(&a, &b);
        assert!(!result.identical);
        assert_eq!(result.differing_bytes, 1);
    }

    #[test]
    fn test_binary_byte_compare_different_length() {
        let a = vec![1, 2, 3];
        let b = vec![1, 2, 3, 4];
        let result = binary_byte_compare(&a, &b);
        assert!(!result.identical);
        assert!(result.differing_bytes > 0);
    }

    // ── IR Comparison ──────────────────────────────────────────────────────

    #[test]
    fn test_ir_line_compare_identical() {
        let a = "define i32 @main() {\n  ret i32 0\n}\n";
        let b = "define i32 @main() {\n  ret i32 0\n}\n";
        let result = ir_line_compare(a, b, false);
        assert!(result.identical);
    }

    #[test]
    fn test_ir_line_compare_different() {
        let a = "define i32 @main() {\n  ret i32 0\n}\n";
        let b = "define i32 @main() {\n  ret i32 1\n}\n";
        let result = ir_line_compare(a, b, false);
        assert!(!result.identical);
    }

    #[test]
    fn test_ir_line_compare_strip_comments() {
        let a = "; Comment line\ndefine i32 @main() {\n  ret i32 0\n}\n";
        let b = "define i32 @main() {\n  ret i32 0\n}\n";
        let result = ir_line_compare(a, b, true);
        assert!(result.identical);
    }

    // ── Hash Computation ───────────────────────────────────────────────────

    #[test]
    fn test_compute_hash_64_basic() {
        let data = b"hello world";
        let hash = compute_hash_64(data);
        assert_eq!(hash.len(), 8);
    }

    #[test]
    fn test_compute_hash_64_deterministic() {
        let data = b"test data";
        let h1 = compute_hash_64(data);
        let h2 = compute_hash_64(data);
        assert_eq!(h1, h2);
    }

    #[test]
    fn test_compute_hash_64_different() {
        let h1 = compute_hash_64(b"hello");
        let h2 = compute_hash_64(b"world");
        assert_ne!(h1, h2);
    }

    // ── Regression Detector ────────────────────────────────────────────────

    #[test]
    fn test_regression_detector_hash_match() {
        let mut detector = RegressionDetector::new();
        detector.set_reference_hash(BootstrapStage::Stage2, vec![1, 2, 3]);
        let status = detector.check_hash(BootstrapStage::Stage2, &[1, 2, 3]);
        assert_eq!(status, RegressionStatus::Match);
    }

    #[test]
    fn test_regression_detector_hash_mismatch() {
        let mut detector = RegressionDetector::new();
        detector.set_reference_hash(BootstrapStage::Stage2, vec![1, 2, 3]);
        let status = detector.check_hash(BootstrapStage::Stage2, &[4, 5, 6]);
        assert_eq!(status, RegressionStatus::BinaryMismatch);
    }

    #[test]
    fn test_regression_detector_no_reference() {
        let detector = RegressionDetector::new();
        let status = detector.check_hash(BootstrapStage::Stage2, &[1, 2, 3]);
        assert_eq!(status, RegressionStatus::NoReference);
    }

    #[test]
    fn test_regression_status_is_regression() {
        assert!(RegressionStatus::BinaryMismatch.is_regression());
        assert!(!RegressionStatus::Match.is_regression());
        assert!(!RegressionStatus::NoReference.is_regression());
    }

    // ── SelfHostDatabase ────────────────────────────────────────────────────

    #[test]
    fn test_database_new() {
        let db = SelfHostDatabase::new();
        assert!(db.is_empty());
    }

    #[test]
    fn test_database_add_record() {
        let mut db = SelfHostDatabase::new();
        db.add_record(SelfHostDatabaseRecord::new("x86_64-linux"));
        assert_eq!(db.len(), 1);
    }

    #[test]
    fn test_database_success_rate() {
        let mut db = SelfHostDatabase::new();
        let mut record = SelfHostDatabaseRecord::new("x86_64-linux");
        record.bootstrap_successful = true;
        db.add_record(record);
        assert!((db.success_rate() - 1.0).abs() < 0.001);
    }

    // ── ComprehensiveBootstrapReport ────────────────────────────────────────

    #[test]
    fn test_report_new() {
        let report = ComprehensiveBootstrapReport::new();
        assert!(!report.overall_success);
    }

    #[test]
    fn test_report_generate_markdown() {
        let report = ComprehensiveBootstrapReport::new();
        let md = report.generate_markdown();
        assert!(md.contains("Bootstrap Self-Hosting Report"));
    }

    // ── BootstrapTestSuite ──────────────────────────────────────────────────

    #[test]
    fn test_bootstrap_test_suite_c_tests() {
        let suite = BootstrapTestSuite::build_default_c_tests();
        assert!(suite.len() >= 10);
    }

    #[test]
    fn test_bootstrap_test_suite_cpp_tests() {
        let suite = BootstrapTestSuite::build_default_cpp_tests();
        assert!(suite.len() >= 5);
    }

    // ── PerformanceRatio ──────────────────────────────────────────────────

    #[test]
    fn test_performance_ratio_summary() {
        let ratio = PerformanceRatio {
            stage_a: BootstrapStage::Stage2,
            stage_b: BootstrapStage::Stage1,
            compile_time_ratio: 0.85,
            binary_size_ratio: 1.05,
            memory_ratio: 1.10,
            ipm_ratio: 1.18,
        };
        let summary = ratio.summary();
        assert!(summary.contains("Stage2"));
        assert!(summary.contains("Stage1"));
    }

    // ── BootstrapVerificationRunner ───────────────────────────────────────

    #[test]
    fn test_verification_runner_new() {
        let config = BootstrapStage2Config::default();
        let runner = BootstrapVerificationRunner::new(config);
        assert!(!runner.report.overall_success);
    }

    #[test]
    fn test_verification_runner_summary() {
        let config = BootstrapStage2Config::default();
        let runner = BootstrapVerificationRunner::new(config);
        let summary = runner.summary();
        assert!(summary.contains("Bootstrap Verification"));
    }

    // ── BinaryDiffResult ───────────────────────────────────────────────────

    #[test]
    fn test_binary_diff_result_identical_summary() {
        let result = BinaryDiffResult {
            identical: true, differing_bytes: 0, a_len: 100, b_len: 100,
            first_diff_offset: None, last_diff_offset: None,
        };
        assert!(result.summary().contains("Byte-identical"));
    }

    // ── IrDiffResult ────────────────────────────────────────────────────────

    #[test]
    fn test_ir_diff_result_identical_summary() {
        let result = IrDiffResult {
            identical: true, diff_lines: 0, a_line_count: 10, b_line_count: 10,
        };
        assert!(result.summary().contains("IR identical"));
    }

    // ── Default Configurations ──────────────────────────────────────────────

    #[test]
    fn test_default_bootstrap_stage2_config() {
        let config = default_bootstrap_stage2_config();
        assert!(config.byte_for_byte_compare);
    }

    #[test]
    fn test_quick_bootstrap_stage2_config() {
        let config = quick_bootstrap_stage2_config();
        assert!(!config.byte_for_byte_compare);
        assert!(!config.verify_determinism);
    }

    #[test]
    fn test_thorough_bootstrap_stage2_config() {
        let config = thorough_bootstrap_stage2_config();
        assert!(config.byte_for_byte_compare);
        assert!(config.verify_determinism);
        assert_eq!(config.determinism_rounds, 5);
    }
}