alef-e2e 0.2.0

//! R e2e test generator using testthat.

use crate::config::E2eConfig;
use crate::escape::{escape_r, sanitize_filename, sanitize_ident};
use crate::field_access::FieldResolver;
use crate::fixture::{Assertion, Fixture, FixtureGroup};
use alef_core::backend::GeneratedFile;
use alef_core::config::AlefConfig;
use anyhow::Result;
use std::fmt::Write as FmtWrite;
use std::path::PathBuf;

use super::E2eCodegen;

/// R e2e code generator.
pub struct RCodegen;

impl E2eCodegen for RCodegen {
    fn generate(
        &self,
        groups: &[FixtureGroup],
        e2e_config: &E2eConfig,
        _alef_config: &AlefConfig,
    ) -> Result<Vec<GeneratedFile>> {
        let lang = self.language_name();
        let output_base = PathBuf::from(&e2e_config.output).join(lang);

        let mut files = Vec::new();

        // Resolve call config with overrides.
        let call = &e2e_config.call;
        let overrides = call.overrides.get(lang);
        let module_path = overrides
            .and_then(|o| o.module.as_ref())
            .cloned()
            .unwrap_or_else(|| call.module.clone());
        let function_name = overrides
            .and_then(|o| o.function.as_ref())
            .cloned()
            .unwrap_or_else(|| call.function.clone());
        let result_var = &call.result_var;

        // Resolve package config.
        let r_pkg = e2e_config.packages.get("r");
        let pkg_name = r_pkg
            .and_then(|p| p.name.as_ref())
            .cloned()
            .unwrap_or_else(|| module_path.clone());

        // Generate DESCRIPTION file.
        files.push(GeneratedFile {
            path: output_base.join("DESCRIPTION"),
            content: render_description(&pkg_name),
            generated_header: false,
        });

        // Generate test runner script.
        files.push(GeneratedFile {
            path: output_base.join("run_tests.R"),
            content: render_test_runner(&pkg_name),
            generated_header: true,
        });

        // Generate test files per category.
        for group in groups {
            let active: Vec<&Fixture> = group
                .fixtures
                .iter()
                .filter(|f| f.skip.as_ref().is_none_or(|s| !s.should_skip(lang)))
                .collect();

            if active.is_empty() {
                continue;
            }

            let filename = format!("test_{}.R", sanitize_filename(&group.category));
            let field_resolver = FieldResolver::new(&e2e_config.fields, &e2e_config.fields_optional);
            let content = render_test_file(
                &group.category,
                &active,
                &function_name,
                result_var,
                &e2e_config.call.args,
                &field_resolver,
            );
            files.push(GeneratedFile {
                path: output_base.join("tests").join(filename),
                content,
                generated_header: true,
            });
        }

        Ok(files)
    }

    fn language_name(&self) -> &'static str {
        "r"
    }
}

fn render_description(pkg_name: &str) -> String {
    format!(
        r#"Package: e2e.r
Title: E2E Tests for {pkg_name}
Version: 0.1.0
Description: End-to-end test suite.
Suggests: testthat (>= 3.0.0)
Config/testthat/edition: 3
"#
    )
}

fn render_test_runner(pkg_name: &str) -> String {
    let mut out = String::new();
    let _ = writeln!(out, "library(testthat)");
    let _ = writeln!(out, "library({pkg_name})");
    let _ = writeln!(out);
    let _ = writeln!(out, "test_dir(\"tests\")");
    out
}

fn render_test_file(
    category: &str,
    fixtures: &[&Fixture],
    function_name: &str,
    result_var: &str,
    args: &[crate::config::ArgMapping],
    field_resolver: &FieldResolver,
) -> String {
    let mut out = String::new();
    let _ = writeln!(out, "# E2e tests for category: {category}");
    let _ = writeln!(out);

    for (i, fixture) in fixtures.iter().enumerate() {
        render_test_case(&mut out, fixture, function_name, result_var, args, field_resolver);
        if i + 1 < fixtures.len() {
            let _ = writeln!(out);
        }
    }

    // Clean up trailing newlines.
    while out.ends_with("\n\n") {
        out.pop();
    }
    if !out.ends_with('\n') {
        out.push('\n');
    }
    out
}

fn render_test_case(
    out: &mut String,
    fixture: &Fixture,
    function_name: &str,
    result_var: &str,
    args: &[crate::config::ArgMapping],
    field_resolver: &FieldResolver,
) {
    let test_name = sanitize_ident(&fixture.id);
    let description = fixture.description.replace('"', "\\\"");

    let expects_error = fixture.assertions.iter().any(|a| a.assertion_type == "error");

    let args_str = build_args_string(&fixture.input, args);

    if expects_error {
        let _ = writeln!(out, "test_that(\"{test_name}: {description}\", {{");
        let _ = writeln!(out, "  expect_error({function_name}({args_str}))");
        let _ = writeln!(out, "}})");
        return;
    }

    let _ = writeln!(out, "test_that(\"{test_name}: {description}\", {{");
    let _ = writeln!(out, "  {result_var} <- {function_name}({args_str})");

    for assertion in &fixture.assertions {
        render_assertion(out, assertion, result_var, field_resolver);
    }

    let _ = writeln!(out, "}})");
}

fn build_args_string(input: &serde_json::Value, args: &[crate::config::ArgMapping]) -> String {
    if args.is_empty() {
        return json_to_r(input);
    }

    let parts: Vec<String> = args
        .iter()
        .filter_map(|arg| {
            let val = input.get(&arg.field)?;
            if val.is_null() && arg.optional {
                return None;
            }
            Some(format!("{} = {}", arg.name, json_to_r(val)))
        })
        .collect();

    parts.join(", ")
}

fn render_assertion(out: &mut String, assertion: &Assertion, result_var: &str, field_resolver: &FieldResolver) {
    let field_expr = match &assertion.field {
        Some(f) if !f.is_empty() => field_resolver.accessor(f, "r", result_var),
        _ => result_var.to_string(),
    };

    match assertion.assertion_type.as_str() {
        "equals" => {
            if let Some(expected) = &assertion.value {
                let r_val = json_to_r(expected);
                let _ = writeln!(out, "  expect_equal(trimws({field_expr}), {r_val})");
            }
        }
        "contains" => {
            if let Some(expected) = &assertion.value {
                let r_val = json_to_r(expected);
                let _ = writeln!(out, "  expect_true(grepl({r_val}, {field_expr}, fixed = TRUE))");
            }
        }
        "contains_all" => {
            if let Some(values) = &assertion.values {
                for val in values {
                    let r_val = json_to_r(val);
                    let _ = writeln!(out, "  expect_true(grepl({r_val}, {field_expr}, fixed = TRUE))");
                }
            }
        }
        "not_contains" => {
            if let Some(expected) = &assertion.value {
                let r_val = json_to_r(expected);
                let _ = writeln!(out, "  expect_false(grepl({r_val}, {field_expr}, fixed = TRUE))");
            }
        }
        "not_empty" => {
            let _ = writeln!(out, "  expect_true(nchar({field_expr}) > 0)");
        }
        "is_empty" => {
            let _ = writeln!(out, "  expect_equal({field_expr}, \"\")");
        }
        "starts_with" => {
            if let Some(expected) = &assertion.value {
                let r_val = json_to_r(expected);
                let _ = writeln!(out, "  expect_true(startsWith({field_expr}, {r_val}))");
            }
        }
        "ends_with" => {
            if let Some(expected) = &assertion.value {
                let r_val = json_to_r(expected);
                let _ = writeln!(out, "  expect_true(endsWith({field_expr}, {r_val}))");
            }
        }
        "min_length" => {
            if let Some(val) = &assertion.value {
                if let Some(n) = val.as_u64() {
                    let _ = writeln!(out, "  expect_true(nchar({field_expr}) >= {n})");
                }
            }
        }
        "max_length" => {
            if let Some(val) = &assertion.value {
                if let Some(n) = val.as_u64() {
                    let _ = writeln!(out, "  expect_true(nchar({field_expr}) <= {n})");
                }
            }
        }
        "not_error" => {
            // Already handled — the call would stop on error.
        }
        "error" => {
            // Handled at the test level.
        }
        other => {
            let _ = writeln!(out, "  # TODO: unsupported assertion type: {other}");
        }
    }
}

/// Convert a `serde_json::Value` to an R literal string.
fn json_to_r(value: &serde_json::Value) -> String {
    match value {
        serde_json::Value::String(s) => format!("\"{}\"", escape_r(s)),
        serde_json::Value::Bool(true) => "TRUE".to_string(),
        serde_json::Value::Bool(false) => "FALSE".to_string(),
        serde_json::Value::Number(n) => n.to_string(),
        serde_json::Value::Null => "NULL".to_string(),
        serde_json::Value::Array(arr) => {
            let items: Vec<String> = arr.iter().map(json_to_r).collect();
            format!("c({})", items.join(", "))
        }
        serde_json::Value::Object(map) => {
            let entries: Vec<String> = map
                .iter()
                .map(|(k, v)| format!("\"{}\" = {}", escape_r(k), json_to_r(v)))
                .collect();
            format!("list({})", entries.join(", "))
        }
    }
}