pub enum IssueRelated {
    OpenProjectIssue(String),
}

pub fn append_related_issues(issue: &IssueRelated, content: &String) -> String {
    let mut splitted = content.lines();
    let mut new_content: Vec<String> = Vec::new();

    let mut found = false;
    let mut iteration_started = false;
    while let Some(line) = splitted.next() {
        if line.contains("## Related issues") {
            found = true;
            new_content.push(line.parse().unwrap());
            // we go to the end of the section
            while let Some(line) = splitted.next() {
                if line.starts_with("-") || line.starts_with("*") {
                    iteration_started = true;
                    new_content.push(line.parse().unwrap());
                } else if (line.trim().is_empty()) && iteration_started {
                    new_content.append(&mut add_related_issues_section(issue));
                    iteration_started = false;
                    found = true;
                    new_content.push(line.parse().unwrap());
                    break;
                } else if line.starts_with("#") {
                    new_content.push("new title found".to_string());
                    found = true;
                    new_content.append(&mut add_related_issues_section(issue));
                    new_content.push("".to_string());
                    new_content.push(line.parse().unwrap());
                    break;
                } else {
                    new_content.push(line.parse().unwrap());
                }
            }
        } else {
            new_content.push(line.parse().unwrap());
        }
    }
    if !found || iteration_started {
        if !found {
            new_content.append(&mut add_related_issues_title());
        }
        new_content.append(&mut add_related_issues_section(issue));
    }

    new_content.join(&"\n")
}

fn add_related_issues_title() -> Vec<String> {
    let mut previous: Vec<String> = Vec::new();
    previous.push("".to_string());
    previous.push("## Related issues".to_string());
    previous.push("".to_string());
    previous
}

fn add_related_issues_section(issue: &IssueRelated) -> Vec<String> {
    let mut previous: Vec<String> = Vec::new();
    previous.push(convert_issue_link_items(issue));

    previous
}

fn convert_issue_link_items(issue: &IssueRelated) -> String {
    match issue {
        IssueRelated::OpenProjectIssue(issue_url) => format!("- [{}]({})", issue_url, issue_url),
    }
}

#[cfg(test)]
mod tests {
    use crate::planning::utils::{append_related_issues, IssueRelated};

    #[test]
    pub fn test_append_related_issues_content_empty() {
        let issue = IssueRelated::OpenProjectIssue("https://example/wp/1".to_string());
        assert_eq!(
            r#"
## Related issues

- [https://example/wp/1](https://example/wp/1)"#,
            append_related_issues(&issue, &("".to_string()))
        );
    }

    #[test]
    pub fn test_append_related_issues_content_not_empty() {
        let issue = IssueRelated::OpenProjectIssue("https://example/wp/1".to_string());
        assert_eq!(
            r#"Something happens.

## Some title

Some content

## Related issues

- [https://example/wp/1](https://example/wp/1)"#,
            append_related_issues(
                &issue,
                &"Something happens.\n\
\n\
## Some title\n\
\n\
Some content"
                    .to_string()
            ),
        );
    }

    #[test]
    pub fn test_append_related_issues_existing_section_related_issues() {
        let issue = IssueRelated::OpenProjectIssue("https://example/wp/1".to_string());
        assert_eq!(
            r#"Something happens.

## Some title

Some content

## Related issues

- [https://example/wp/2](https://example/wp/2)
- [https://example/wp/1](https://example/wp/1)"#,
            append_related_issues(
                &issue,
                &r#"Something happens.

## Some title

Some content

## Related issues

- [https://example/wp/2](https://example/wp/2)"#
                    .to_string()
            ),
        );
    }

    #[test]
    pub fn test_append_related_issues_existing_section_related_issues_not_last() {
        let issue = IssueRelated::OpenProjectIssue("https://example/wp/1".to_string());
        assert_eq!(
            r#"Something happens.

## Some title

Some content

## Related issues

- [https://example/wp/2](https://example/wp/2)
- [https://example/wp/1](https://example/wp/1)

## Other content

Some other content"#,
            append_related_issues(
                &issue,
                &r#"Something happens.

## Some title

Some content

## Related issues

- [https://example/wp/2](https://example/wp/2)

## Other content

Some other content"#
                    .to_string()
            ),
        );
    }
}