use anyhow::Result;
use chrono::Local;
use html2md::parse_html;
use megalodon::{
    entities::{Account, Attachment, Status},
    response::Response,
    Megalodon,
};
use regex::{Captures, Regex};
use rustyline::DefaultEditor;
use url::Url;
use url_open::UrlOpen;

pub(super) async fn format_status(
    client: &Box<dyn Megalodon + Send + Sync>,
    depth: usize,
    account: &Account,
    status: &Status,
) -> Result<String> {
    let time_prefix = quote_prefix(0);
    let ancestor_prefix = quote_prefix(depth);
    let ancestor = format!(
        "{time_prefix}{timestamp}
{ancestor_prefix}{status}{attachments}",
        time_prefix = time_prefix,
        timestamp = status.created_at.with_timezone(&Local).format("%H:%M"),
        ancestor_prefix = ancestor_prefix,
        status = apply_block_quote(depth, parse_html(&status.content).trim()),
        attachments = format_attachments(depth, &status.media_attachments)
    );
    let Response { json, .. } = client.get_status_context(status.id.clone(), None).await?;
    let descendant_prefix = quote_prefix(depth + 1);
    let thread = json
        .descendants
        .into_iter()
        .filter(|s| {
            s.in_reply_to_account_id == Some(account.id.clone()) && s.account.id == account.id
        })
        .map(|status| {
            format!(
                "{ancestor_prefix}
{ancestor_prefix}{timestamp}
{descendant_prefix}{status}{attachments}",
                ancestor_prefix = ancestor_prefix,
                timestamp = status.created_at.with_timezone(&Local).format("%H:%M"),
                descendant_prefix = descendant_prefix,
                status = apply_block_quote(depth + 1, parse_html(&status.content).trim()),
                attachments = format_attachments(depth + 1, &status.media_attachments)
            )
        })
        .collect::<Vec<String>>()
        .join("\n");
    Ok(format!(
        "{}{}",
        ancestor,
        if thread.is_empty() {
            String::default()
        } else {
            format!("\n{}", thread)
        }
    ))
}

fn quote_prefix(depth: usize) -> String {
    if depth == 0 {
        String::default()
    } else {
        format!("{} ", vec![">"; depth].join(""))
    }
}

fn format_attachments(depth: usize, attachments: &[Attachment]) -> String {
    if attachments.is_empty() {
        String::default()
    } else {
        format!(
            "\n{}",
            attachments
                .iter()
                .map(|a| {
                    Url::parse(&a.url).unwrap().open();
                    let mut editor = DefaultEditor::new().unwrap();
                    let src = if let Ok(line) = editor.readline("Filename: ") {
                        line
                    } else {
                        a.url.clone()
                    };
                    format!("{} <img src=\"{}\" />", quote_prefix(depth), src)
                })
                .collect::<Vec<String>>()
                .join("\n")
        )
    }
}

// without processing the content per line, the block quote markdown is only added to the first
// line, breaking the desired formatting
fn apply_block_quote<S: AsRef<str>>(depth: usize, content: S) -> String {
    let prefix = quote_prefix(depth);
    let empty = Regex::new("\n\\s").expect("Failed to compiled regex for nested empty lines!");
    let non_empty =
        Regex::new("\n(?P<initial>[^>\\s])").expect("Failed to compile regex for nested lines!");
    // parsing some multiline content adds paragraph tags, convert those back to new lines to apply
    // the block quote level to each line
    let content = content.as_ref().replace("</p><p>", "\n\n");
    let content = content.replace("<p>", "");
    let content = content.replace("</p>", "");
    // replace separately to avoid trailing spaces when replacing empty lines with the prefix
    let content = empty.replace_all(content.as_ref(), format!("\n{}\n", prefix.trim()));
    let content = non_empty.replace_all(&content, |c: &Captures| {
        format!("\n{}{}", prefix, c["initial"].to_string())
    });
    content.to_string()
}

#[cfg(test)]
mod test {
    use crate::format::apply_block_quote;

    #[test]
    fn test_apply_bq() {
        assert_eq!(
            "Foo
>
> Bar"
                .to_owned(),
            apply_block_quote(
                1, "Foo

Bar"
            )
        );
    }

    #[test]
    fn test_apply_bq_deeper() {
        assert_eq!(
            "Foo
>>
>> Bar"
                .to_owned(),
            apply_block_quote(
                2, "Foo

Bar"
            )
        );
    }

    #[test]
    fn test_apply_bq_strip_ps() {
        assert_eq!(
            "Foo
>>
>> Bar"
                .to_owned(),
            apply_block_quote(2, "<p>Foo</p><p>Bar</p>")
        );
    }
}