use crate::template::{Context, find, parse};
use std::fs::write;
use std::io::{Error, Result};
use std::path::Path;

const FILENAME: &str = "index.html";

pub fn generate(
    _: &Path,
    template_directory: &Path,
    target: &Path,
    context: &Context,
) -> Result<()> {
    if let Some(template) = find(template_directory, FILENAME) {
        let parsed_template =
            parse(&template).ok_or_else(|| Error::other("Unable to parse HTML template"))?;
        let rendered_template = parsed_template.render(context)?;
        let location = target.join(FILENAME);
        write(location, rendered_template)?;
    }
    Ok(())
}

#[cfg(test)]
mod tests {
    use std::collections::HashMap;
    use std::fs::create_dir_all;

    use super::*;

    use crate::template::Value;

    use test_utilities::*;

    #[test]
    fn test_generates_html_with_default_layout() {
        let test_dir = setup_test_dir();
        let static_dir = test_dir.join("static");
        let template_dir = test_dir.join("templates");
        let output_dir = test_dir.join("output");

        create_dir_all(&static_dir).expect("Could not create static directory");
        create_dir_all(&template_dir).expect("Could not create template directory");
        create_dir_all(&output_dir).expect("Could not create output directory");

        let context = HashMap::from([
            ("has_posts".to_string(), Value::Bool(true)),
            (
                "posts".to_string(),
                Value::Collection(vec![
                    HashMap::from([
                        ("index".to_string(), Value::Unsigned(2828)),
                        (
                            "html".to_string(),
                            Value::String("<p>Contextualization</p>".to_string()),
                        ),
                    ]),
                    HashMap::from([
                        ("index".to_string(), Value::Unsigned(2828)),
                        (
                            "html".to_string(),
                            Value::String("<p>Contexternalization</p>".to_string()),
                        ),
                    ]),
                ]),
            ),
        ]);

        generate(&static_dir, &template_dir, &output_dir, &context).expect("Generate failed");

        assert_file_contains(&output_dir.join("index.html"), "<p>Contextualization</p>");
        assert_file_contains(&output_dir.join("index.html"), "<p>Contexternalization</p>");
        cleanup_test_dir(&test_dir);
    }

    #[test]
    fn test_uses_custom_layout_if_available() {
        let test_dir = setup_test_dir();
        let static_dir = test_dir.join("static");
        let template_dir = test_dir.join("templates");
        let output_dir = test_dir.join("output");

        create_dir_all(&static_dir).expect("Could not create static directory");
        create_dir_all(&template_dir).expect("Could not create template directory");
        create_dir_all(&output_dir).expect("Could not create output directory");
        create_test_file(
            &template_dir.join("index.html"),
            "\
{{~ posts:post }}
    {{= post.html }}
{{~}}
",
        );
        let context = HashMap::from([(
            "posts".to_string(),
            Value::Collection(vec![
                HashMap::from([(
                    "html".to_string(),
                    Value::String("<p>Recontextualization</p>".to_string()),
                )]),
                HashMap::from([(
                    "html".to_string(),
                    Value::String("<p>Recontexternalization</p>".to_string()),
                )]),
            ]),
        )]);

        generate(&static_dir, &template_dir, &output_dir, &context).expect("Generate failed");

        assert_file_contents(
            &output_dir.join("index.html"),
            "\
<p>Recontextualization</p>

    <p>Recontexternalization</p>
",
        );
        cleanup_test_dir(&test_dir);
    }

    #[test]
    fn test_fails_if_html_is_malformed() {
        let test_dir = setup_test_dir();
        let static_dir = test_dir.join("static");
        let template_dir = test_dir.join("templates");
        let output_dir = test_dir.join("output");

        create_dir_all(&static_dir).expect("Could not create static directory");
        create_dir_all(&template_dir).expect("Could not create template directory");
        create_dir_all(&output_dir).expect("Could not create output directory");
        create_test_file(
            &template_dir.join("index.html"),
            "\
{{~ posts:post }}
    {{ post.html }}
{{~}}
",
        );
        let context = HashMap::new();

        let result = generate(&static_dir, &template_dir, &output_dir, &context);

        assert!(result.is_err());
        cleanup_test_dir(&test_dir);
    }

    #[test]
    fn test_fails_if_output_is_not_writable() {
        let test_dir = setup_test_dir();
        let static_dir = test_dir.join("static");
        let template_dir = test_dir.join("templates");
        let output_dir = test_dir.join("output");

        create_dir_all(&template_dir).expect("Could not create template directory");
        create_test_file(
            &template_dir.join("index.html"),
            "\
{{~ posts:post }}
    {{= post.html }}
{{~}}
",
        );
        let context = HashMap::from([(
            "posts".to_string(),
            Value::Collection(vec![
                HashMap::from([(
                    "html".to_string(),
                    Value::String("<p>Recontextualization</p>".to_string()),
                )]),
                HashMap::from([(
                    "html".to_string(),
                    Value::String("<p>Recontexternalization</p>".to_string()),
                )]),
            ]),
        )]);

        let result = generate(&static_dir, &template_dir, &output_dir, &context);

        assert!(result.is_err());
        cleanup_test_dir(&test_dir);
    }
}