use std::fs;
use std::fs::File;
use std::io::Write;
use std::path::Path;

fn main() {
  println!("cargo:rerun-if-changed=tests/fixtures");
  println!("cargo:rerun-if-changed=Cargo.toml");

  // File 1: src/tests.rs for #[pg_test]
  let pg_dest_path = Path::new("src/tests.rs");
  let mut pg_file = File::create(&pg_dest_path).unwrap();

  // File 2: tests/tests.rs for standard #[test] integration
  let std_dest_path = Path::new("tests/tests.rs");
  let mut std_file = File::create(&std_dest_path).unwrap();

  // Write headers
  writeln!(std_file, "use jspg::util;").unwrap();

  // Helper for snake_case conversion
  let to_snake_case = |s: &str| -> String {
    s.chars().fold(String::new(), |mut acc, c| {
      if c.is_uppercase() {
        if !acc.is_empty() {
          acc.push('_');
        }
        acc.push(c.to_ascii_lowercase());
      } else if c == '-' || c == ' ' || c == '.' || c == '/' || c == ':' {
        acc.push('_');
      } else if c.is_alphanumeric() {
        acc.push(c);
      }
      acc
    })
  };

  // Walk tests/fixtures directly
  let fixtures_path = "tests/fixtures";
  if Path::new(fixtures_path).exists() {
    for entry in fs::read_dir(fixtures_path).unwrap() {
      let entry = entry.unwrap();
      let path = entry.path();
      if path.extension().unwrap_or_default() == "json" {
        let file_name = path.file_stem().unwrap().to_str().unwrap();

        // Parse the JSON file to find blocks
        let file = File::open(&path).unwrap();
        let val: serde_json::Value = serde_json::from_reader(file).unwrap();

        if let Some(arr) = val.as_array() {
          for (i, _item) in arr.iter().enumerate() {
            // Use short, deterministic names to avoid Postgres 63-byte limit
            // e.g. test_dynamic_ref_case_0
            let fn_name = format!("test_{}_case_{}", to_snake_case(file_name), i);

            // Write to src/tests.rs (PG Test)
            write!(
              pg_file,
              r#"
#[pg_test]
fn {}() {{
    let path = format!("{{}}/tests/fixtures/{}.json", env!("CARGO_MANIFEST_DIR"));
    crate::util::run_test_file_at_index(&path, {}).unwrap();
}}
"#,
              fn_name, file_name, i
            )
            .unwrap();

            // Write to tests/tests.rs (Std Test)
            write!(
              std_file,
              r#"
#[test]
fn {}() {{
    let path = format!("{{}}/tests/fixtures/{}.json", env!("CARGO_MANIFEST_DIR"));
    util::run_test_file_at_index(&path, {}).unwrap();
}}
"#,
              fn_name, file_name, i
            )
            .unwrap();
          }
        }
      }
    }
  }
}