//! End-to-end tests: string input → final output.

use std::collections::HashMap;
use std::sync::Arc;
use symclaw_core::ast::Expr;
use symclaw_core::interner::Symbol;
use symclaw_core::{
    codegen, differentiate, eval, integrate, limits, number_theory, parser, poly, proof, series,
    simplify, solve,
};

fn parse(s: &str) -> Arc<Expr> {
    parser::parse(s).unwrap()
}

// ── 1. Differentiate x^3 ───────────────────────────────────────

#[test]
fn e2e_differentiate_x_cubed() {
    let expr = parse("x^3");
    let deriv = differentiate::differentiate(&expr, Symbol::new("x"));
    let simplified = simplify::simplify(&deriv);
    let s = format!("{simplified}");
    assert!(s.contains("3") && s.contains("x"), "d/dx(x^3) = {s}");
}

// ── 2. Integrate sin(x) ────────────────────────────────────────

#[test]
fn e2e_integrate_sin() {
    let expr = parse("sin(x)");
    let result = integrate::integrate(&expr, Symbol::new("x")).unwrap();
    let s = format!("{result}");
    assert!(s.contains("cos"), "∫sin(x)dx should contain cos: {s}");
}

// ── 3. Solve x^2 - 4 = 0 ───────────────────────────────────────

#[test]
fn e2e_solve_quadratic() {
    let expr = parse("x^2 - 4");
    let sols = solve::solve(&expr, Symbol::new("x"));
    assert_eq!(sols.len(), 2, "x^2-4=0 should have 2 solutions");
    let strs: Vec<String> = sols.iter().map(|s| format!("{s}")).collect();
    assert!(strs.contains(&"2".to_owned()) || strs.iter().any(|s| s.contains("2")));
}

// ── 4. Limit sin(x)/x → 1 ──────────────────────────────────────

#[test]
fn e2e_limit_sinc() {
    let expr = parse("sin(x)/x");
    let result = limits::limit_at(&expr, "x", 0.0);
    match result {
        limits::LimitResult::Finite(e) => {
            let s = format!("{e}");
            assert!(s == "1" || s.starts_with("1"), "limit = {s}");
        }
        other => panic!("expected 1, got {other:?}"),
    }
}

// ── 5. Taylor expansion of exp(x) ──────────────────────────────

#[test]
fn e2e_taylor_exp() {
    let expr = parse("exp(x)");
    let point = parse("0");
    let expansion = series::taylor(&expr, Symbol::new("x"), &point, 5);
    // Check it evaluates correctly at x=0.5
    let mut vars = HashMap::new();
    vars.insert(Symbol::new("x"), 0.5);
    let val = eval::eval(&expansion, &vars).unwrap();
    assert!((val - 0.5_f64.exp()).abs() < 0.01);
}

// ── 6. Simplify (x+1)*(x-1) ────────────────────────────────────

#[test]
fn e2e_simplify_expand() {
    let expr = parse("(x+1)*(x-1)");
    let simplified = simplify::simplify(&expr);
    let s = format!("{simplified}");
    // Should simplify to x^2 - 1 or equivalent
    assert!(
        s.contains("x") && (s.contains("-1") || s.contains("x^2")),
        "got: {s}"
    );
}

// ── 7. Proof trace ──────────────────────────────────────────────

#[test]
fn e2e_proof_trace() {
    let expr = parse("x + 0");
    let trace = proof::trace_simplify(&expr);
    assert_eq!(trace.result, "x");
}

// ── 8. Codegen to Python ────────────────────────────────────────

#[test]
fn e2e_codegen_python() {
    let expr = parse("x^2 + y");
    let opts = codegen::CodegenOptions::new(codegen::Language::Python);
    let code = codegen::generate(&expr, &opts);
    assert!(
        code.contains("**") || code.contains("pow"),
        "Python code: {code}"
    );
}

// ── 9. Number theory: is_prime ──────────────────────────────────

#[test]
fn e2e_is_prime() {
    assert!(number_theory::is_prime(97));
    assert!(!number_theory::is_prime(42));
}

// ── 10. Number theory: factorize ────────────────────────────────

#[test]
fn e2e_factorize() {
    let factors = number_theory::factorize(360);
    assert_eq!(factors, vec![(2, 3), (3, 2), (5, 1)]);
}

// ── 11. Polynomial conversion ───────────────────────────────────

#[test]
fn e2e_polynomial() {
    let expr = parse("x^3 + 2*x^2 + x");
    let p = poly::Polynomial::from_expr(&expr).unwrap();
    let back = p.to_expr();
    let s = format!("{}", Arc::new(back));
    assert!(s.contains("x"), "poly roundtrip: {s}");
}

// ── 12. Solve linear equation ───────────────────────────────────

#[test]
fn e2e_solve_linear() {
    let expr = parse("2*x - 6");
    let sols = solve::solve(&expr, Symbol::new("x"));
    assert!(!sols.is_empty());
    let strs: Vec<String> = sols.iter().map(|s| format!("{s}")).collect();
    assert!(strs.contains(&"3".to_owned()));
}

// ── 13. Differentiate trig ──────────────────────────────────────

#[test]
fn e2e_differentiate_cos() {
    let expr = parse("cos(x)");
    let deriv = differentiate::differentiate(&expr, Symbol::new("x"));
    let s = format!("{}", simplify::simplify(&deriv));
    assert!(s.contains("sin"), "d/dx(cos(x)) = {s}");
}

// ── 14. Eval with variables ─────────────────────────────────────

#[test]
fn e2e_eval_with_vars() {
    let expr = parse("x^2 + y");
    let mut vars = HashMap::new();
    vars.insert(Symbol::new("x"), 3.0);
    vars.insert(Symbol::new("y"), 1.0);
    let val = eval::eval(&expr, &vars).unwrap();
    assert!((val - 10.0).abs() < 1e-10);
}

// ── 15. Fibonacci ───────────────────────────────────────────────

#[test]
fn e2e_fibonacci() {
    assert_eq!(number_theory::fibonacci(10), 55);
    assert_eq!(number_theory::fibonacci(0), 0);
    assert_eq!(number_theory::fibonacci(1), 1);
}

// ── 16. Simplify nested ────────────────────────────────────────

#[test]
fn e2e_simplify_nested() {
    let expr = parse("(x * 1) + (0 + y)");
    let simplified = simplify::simplify(&expr);
    let s = format!("{simplified}");
    assert!(s.contains("x") && s.contains("y"), "simplified: {s}");
}