//! Micropub client: `q=config` and create.

use reqwest::{StatusCode, blocking::Client as Http};
use serde::Deserialize;
use serde_json::{Value, json};
use url::Url;

#[derive(Debug, Clone, Deserialize, PartialEq)]
pub struct SyndicationTarget {
    pub uid: String,
    pub name: String,
}

#[derive(Debug, Clone, Default, Deserialize)]
pub struct ServerConfig {
    #[serde(rename = "syndicate-to", default)]
    pub syndicate_to: Vec<SyndicationTarget>,
}

#[derive(Debug, Clone, Default, PartialEq)]
pub struct Note {
    pub title: Option<String>,
    pub content: String,
    pub tags: Vec<String>,
    /// `None` leaves syndication to the server's default. `Some(vec![])` means none.
    pub syndicate_to: Option<Vec<String>>,
}

impl Note {
    /// Micropub JSON create body. JSON (not form encoding) is the only way to send
    /// an empty `mp-syndicate-to`, which tells the server "crosspost nowhere".
    pub fn to_json(&self) -> Value {
        let mut props = serde_json::Map::new();
        props.insert("content".into(), json!([self.content]));
        if let Some(t) = self.title.as_deref().filter(|t| !t.is_empty()) {
            props.insert("name".into(), json!([t]));
        }
        if !self.tags.is_empty() {
            props.insert("category".into(), json!(self.tags));
        }
        let mut body = json!({ "type": ["h-entry"], "properties": props });
        if let Some(targets) = &self.syndicate_to {
            body["mp-syndicate-to"] = json!(targets);
        }
        body
    }
}

/// Split "a, #b,, a" into ["a", "b"].
pub fn parse_tags(input: &str) -> Vec<String> {
    let mut out: Vec<String> = Vec::new();
    for tag in input.split(',') {
        let tag = tag.trim().trim_start_matches('#').trim();
        if !tag.is_empty() && !out.iter().any(|t| t.eq_ignore_ascii_case(tag)) {
            out.push(tag.to_string());
        }
    }
    out
}

#[derive(Debug, thiserror::Error)]
pub enum Error {
    #[error("not authorized: {0}. Run `tuipub login` again.")]
    Unauthorized(String),
    #[error("{error}: {description}")]
    Server {
        status: StatusCode,
        error: String,
        description: String,
    },
    #[error("server returned {0} without a Location header")]
    NoLocation(StatusCode),
    #[error("network error: {0}")]
    Http(#[from] reqwest::Error),
}

#[derive(Deserialize)]
struct ErrorBody {
    error: String,
    #[serde(default)]
    error_description: String,
}

pub struct Client {
    http: Http,
    endpoint: Url,
    token: String,
}

impl Client {
    pub fn new(http: Http, endpoint: Url, token: String) -> Self {
        Client {
            http,
            endpoint,
            token,
        }
    }

    fn check(resp: reqwest::blocking::Response) -> Result<reqwest::blocking::Response, Error> {
        let status = resp.status();
        if status.is_success() {
            return Ok(resp);
        }
        let body = resp.text().unwrap_or_default();
        let (error, description) = match serde_json::from_str::<ErrorBody>(&body) {
            Ok(b) => (b.error, b.error_description),
            Err(_) => (
                status.canonical_reason().unwrap_or("error").to_string(),
                body.chars().take(200).collect(),
            ),
        };
        if status == StatusCode::UNAUTHORIZED
            || status == StatusCode::FORBIDDEN
            || error == "insufficient_scope"
        {
            let why = if description.is_empty() {
                error
            } else {
                description
            };
            return Err(Error::Unauthorized(why));
        }
        Err(Error::Server {
            status,
            error,
            description,
        })
    }

    fn query(&self, q: &str) -> Result<reqwest::blocking::Response, Error> {
        let mut url = self.endpoint.clone();
        url.query_pairs_mut().append_pair("q", q);
        let resp = self
            .http
            .get(url)
            .bearer_auth(&self.token)
            .header("Accept", "application/json")
            .send()?;
        Self::check(resp)
    }

    pub fn config(&self) -> Result<ServerConfig, Error> {
        let mut cfg: ServerConfig = self.query("config")?.json()?;
        // syndicate-to is optional in q=config; some servers only answer q=syndicate-to.
        if cfg.syndicate_to.is_empty()
            && let Ok(resp) = self.query("syndicate-to")
            && let Ok(s) = resp.json::<ServerConfig>()
        {
            cfg.syndicate_to = s.syndicate_to;
        }
        Ok(cfg)
    }

    /// Publish a note. Returns the post's permalink.
    pub fn create(&self, note: &Note) -> Result<String, Error> {
        let resp = self
            .http
            .post(self.endpoint.clone())
            .bearer_auth(&self.token)
            .header("Accept", "application/json")
            .json(&note.to_json())
            .send()?;
        let resp = Self::check(resp)?;
        let status = resp.status();
        let location = resp
            .headers()
            .get("location")
            .and_then(|v| v.to_str().ok())
            .ok_or(Error::NoLocation(status))?;
        Ok(self
            .endpoint
            .join(location)
            .map(|u| u.to_string())
            .unwrap_or_else(|_| location.to_string()))
    }
}

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

    fn client(server: &MockServer) -> Client {
        Client::new(
            Http::new(),
            Url::parse(&server.url("/micropub")).unwrap(),
            "tok".into(),
        )
    }

    #[test]
    fn tags_are_trimmed_and_deduped() {
        assert_eq!(
            parse_tags(" rust, #tui,,Rust , indieweb "),
            vec!["rust", "tui", "indieweb"]
        );
        assert!(parse_tags("  ,  ").is_empty());
    }

    #[test]
    fn note_json_shape() {
        let note = Note {
            title: Some("Hi".into()),
            content: "Hello **world**".into(),
            tags: vec!["a".into()],
            syndicate_to: Some(vec![]),
        };
        assert_eq!(
            note.to_json(),
            json!({
                "type": ["h-entry"],
                "properties": {"content": ["Hello **world**"], "name": ["Hi"], "category": ["a"]},
                "mp-syndicate-to": []
            })
        );
        let bare = Note {
            content: "x".into(),
            title: Some(String::new()),
            ..Default::default()
        };
        assert_eq!(
            bare.to_json(),
            json!({"type": ["h-entry"], "properties": {"content": ["x"]}})
        );
    }

    #[test]
    fn config_reads_targets() {
        let server = MockServer::start();
        let m = server.mock(|when, then| {
            when.method(GET)
                .path("/micropub")
                .query_param("q", "config")
                .header("authorization", "Bearer tok");
            then.status(200).json_body(json!({
                "media-endpoint": "https://example.com/micropub/media",
                "syndicate-to": [{"uid": "gotosocial", "name": "GoToSocial"}],
                "post-types": []
            }));
        });
        let cfg = client(&server).config().unwrap();
        m.assert();
        assert_eq!(
            cfg.syndicate_to,
            vec![SyndicationTarget {
                uid: "gotosocial".into(),
                name: "GoToSocial".into()
            }]
        );
    }

    #[test]
    fn config_falls_back_to_syndicate_to_query() {
        let server = MockServer::start();
        server.mock(|when, then| {
            when.method(GET)
                .path("/micropub")
                .query_param("q", "config");
            then.status(200).json_body(json!({}));
        });
        server.mock(|when, then| {
            when.method(GET)
                .path("/micropub")
                .query_param("q", "syndicate-to");
            then.status(200)
                .json_body(json!({"syndicate-to": [{"uid": "x", "name": "X"}]}));
        });
        assert_eq!(client(&server).config().unwrap().syndicate_to.len(), 1);
    }

    #[test]
    fn create_posts_json_and_resolves_location() {
        let server = MockServer::start();
        let note = Note {
            content: "hello".into(),
            syndicate_to: Some(vec!["gts".into()]),
            ..Default::default()
        };
        let m = server.mock(|when, then| {
            when.method(POST)
                .path("/micropub")
                .header("authorization", "Bearer tok")
                .json_body(note.to_json());
            then.status(201).header("Location", "/notes/hello");
        });
        let url = client(&server).create(&note).unwrap();
        m.assert();
        assert_eq!(url, server.url("/notes/hello"));
    }

    #[test]
    fn create_maps_errors() {
        let server = MockServer::start();
        server.mock(|when, then| {
            when.method(POST).path("/micropub");
            then.status(403).json_body(json!({"error": "insufficient_scope", "error_description": "Token lacks create scope"}));
        });
        let err = client(&server)
            .create(&Note {
                content: "x".into(),
                ..Default::default()
            })
            .unwrap_err();
        assert!(
            matches!(err, Error::Unauthorized(ref d) if d.contains("create scope")),
            "{err}"
        );

        let server = MockServer::start();
        server.mock(|when, then| {
            when.method(POST).path("/micropub");
            then.status(400).json_body(
                json!({"error": "invalid_request", "error_description": "Content is required"}),
            );
        });
        let err = client(&server).create(&Note::default()).unwrap_err();
        assert_eq!(err.to_string(), "invalid_request: Content is required");

        let server = MockServer::start();
        server.mock(|when, then| {
            when.method(POST).path("/micropub");
            then.status(201);
        });
        let err = client(&server)
            .create(&Note {
                content: "x".into(),
                ..Default::default()
            })
            .unwrap_err();
        assert!(matches!(err, Error::NoLocation(_)));
    }
}