use super::{CalendarUi, EventInstance, Parameters, SimpleDownload};
use crate::prelude::*;
use chrono::DateTime;

#[derive(Clone, Deserialize)]
struct SillyDownloadable {
    /// URL to scrape to download the file from
    download_url: Url,

    /// Disk location to cache the file for debugging
    file_path: Utf8PathBuf,
}

#[derive(Clone, Deserialize)]
pub(crate) struct Config {
    #[serde(flatten)]
    dl: SillyDownloadable,

    #[serde(flatten)]
    pub(crate) ui: CalendarUi,
}

impl Config {
    pub(crate) fn simple_download(&self, now: DateTime<chrono_tz::Tz>) -> SimpleDownload {
        let date = now.format("%Y-%m-%d").to_string();
        let mut url = self.dl.download_url.clone();
        url.query_pairs_mut().append_pair("date", &date);

        SimpleDownload {
            download_url: Some(url),
            file_path: self.dl.file_path.clone(),
        }
    }
}

#[derive(Deserialize)]
struct Event {
    #[serde(alias = "durationInMinutes")]
    duration_in_minutes: u32,
    timestamp: i64,
    title: String,
    description: String,
}

#[derive(Deserialize)]
struct Data {
    items: Vec<Event>,
}

/// The bit that we deserialize directly from JSON
#[derive(Deserialize)]
struct CalendarInner {
    data: Data,
}

pub(crate) struct Calendar {
    config: Config,
    inner: CalendarInner,
}

impl Calendar {
    fn to_event_instance(&self, params: &Parameters, ev: &Event) -> Result<Option<EventInstance>> {
        let dt = DateTime::from_timestamp_millis(ev.timestamp)
            .context("cannot represent timestamp as a date")?
            .with_timezone(&params.tz);
        let dtstart = crate::DatePerhapsTime { dt, all_day: false };
        if dtstart.dt < params.output_start || dtstart.dt > params.output_stop {
            return Ok(None);
        }

        Ok(Some(EventInstance {
            calendar_ui: self.config.ui.clone(),
            dtstart,
            location: None,
            recurrence_id: None,
            summary: Some(ev.title.clone()),
            uid: None,
            url: None,
        }))
    }

    pub(crate) fn event_instances(&self, params: &Parameters) -> Result<Vec<EventInstance>> {
        self.inner
            .data
            .items
            .iter()
            .filter_map(|ev| self.to_event_instance(params, ev).transpose())
            .collect()
    }

    pub(crate) fn read_from_str(config: Config, s: &str) -> Result<Self> {
        let inner = serde_json::from_str(s)?;
        Ok(Self { config, inner })
    }

    pub(crate) fn read_from_config(config: Config) -> Result<Self> {
        let s = std::fs::read_to_string(&config.dl.file_path)?;
        Self::read_from_str(config, &s)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn example_config() -> Config {
        Config {
            dl: SillyDownloadable {
                download_url: Url::parse("https://www.commoninja.com/api/apps/calendar/get-monthly-events?widgetId=00000000-0000-0000-000000000000").unwrap(),
                file_path: ".".into(),
            },
            ui: CalendarUi {
                html_url: None,
                short_name: "asdf".into(),
            },
        }
    }

    #[test]
    fn end_to_end() {
        let s = r#"
{"data":{"items":[{"timestamp":1748989800000,"durationInMinutes":90,"title":"Foo Bar","description":""},{"timestamp":1749999600000,"durationInMinutes":30,"title":"Snaf Oo","description":""}]},"success":true,"message":""}
        "#;

        let cfg = example_config();
        let cal = Calendar::read_from_str(cfg, s).unwrap();
        let params = Parameters::new(
            DateTime::from_timestamp(1748989700, 0)
                .unwrap()
                .with_timezone(&chrono_tz::America::Chicago),
        )
        .unwrap();
        let instances = cal.event_instances(&params).unwrap();

        assert_eq!(instances.len(), 2);
    }

    #[test]
    fn unsillify() {
        let dt = DateTime::from_timestamp(1756190298, 0)
            .unwrap()
            .with_timezone(&chrono_tz::America::Chicago);
        let cfg = example_config();
        assert_eq!(
            cfg.simple_download(dt).download_url.unwrap().to_string(),
            "https://www.commoninja.com/api/apps/calendar/get-monthly-events?widgetId=00000000-0000-0000-000000000000&date=2025-08-26"
        );
    }
}