use anyhow::{Context, Result, anyhow};
use reqwest::header::{HeaderMap, HeaderName, HeaderValue};
use serde::{Deserialize, Serialize};
use uuid::Uuid;

use crate::config::Config;

const CLIENT_NAME: &str = "EmbyTuiClient";
const CLIENT_VERSION: &str = env!("CARGO_PKG_VERSION");
const DEVICE_NAME: &str = "emby-client-tui";

#[derive(Debug, Clone)]
pub struct Client {
    http: reqwest::Client,
    pub server: String,
    pub user_id: String,
    pub user_name: String,
    pub token: String,
    pub device_id: String,
}

#[derive(Debug, Serialize)]
struct AuthRequest<'a> {
    #[serde(rename = "Username")]
    username: &'a str,
    #[serde(rename = "Pw")]
    pw: &'a str,
}

#[derive(Debug, Deserialize)]
struct AuthResponse {
    #[serde(rename = "AccessToken")]
    access_token: String,
    #[serde(rename = "User")]
    user: AuthUser,
}

#[derive(Debug, Deserialize)]
struct AuthUser {
    #[serde(rename = "Id")]
    id: String,
    #[serde(rename = "Name")]
    name: String,
}

#[derive(Debug, Clone, Deserialize, Default)]
pub struct Item {
    #[serde(rename = "Id")]
    pub id: String,
    #[serde(rename = "Name")]
    pub name: String,
    #[serde(rename = "Type", default)]
    pub item_type: String,
    #[serde(rename = "IsFolder", default)]
    pub is_folder: bool,
    #[serde(rename = "ProductionYear", default)]
    pub year: Option<i32>,
    #[serde(rename = "RunTimeTicks", default)]
    pub runtime_ticks: Option<i64>,
    #[serde(rename = "SeriesName", default)]
    pub series_name: Option<String>,
    /// Set for Episode items. Lets us fetch the full series episode list so a
    /// queue started mid-show can continue past the current season.
    #[serde(rename = "SeriesId", default)]
    pub series_id: Option<String>,
    #[serde(rename = "IndexNumber", default)]
    pub index_number: Option<i32>,
    #[serde(rename = "ParentIndexNumber", default)]
    pub parent_index_number: Option<i32>,
    #[serde(rename = "UserData", default)]
    pub user_data: Option<UserData>,
}

impl Item {
    /// Human-readable label suitable for status lines and mpv's force-media-title.
    /// Episodes get "Series — SxxEyy — Title"; movies get "Name (Year)".
    pub fn display_title(&self) -> String {
        if self.item_type == "Episode" {
            let series = self.series_name.as_deref().unwrap_or("");
            let code = match (self.parent_index_number, self.index_number) {
                (Some(s), Some(e)) => format!("S{s:02}E{e:02}"),
                (None, Some(e)) => format!("E{e:02}"),
                _ => String::new(),
            };
            let mut parts: Vec<String> = Vec::new();
            if !series.is_empty() {
                parts.push(series.to_string());
            }
            if !code.is_empty() {
                parts.push(code);
            }
            parts.push(self.name.clone());
            parts.join(" — ")
        } else if let Some(year) = self.year {
            format!("{} ({year})", self.name)
        } else {
            self.name.clone()
        }
    }
}

#[derive(Debug, Clone, Deserialize, Default)]
pub struct UserData {
    #[serde(rename = "PlaybackPositionTicks", default)]
    pub position_ticks: i64,
    #[serde(rename = "PlayedPercentage", default)]
    pub played_percentage: Option<f64>,
}

#[derive(Debug, Deserialize)]
struct ItemsResponse {
    #[serde(rename = "Items", default)]
    items: Vec<Item>,
}

impl Client {
    pub async fn new(cfg: &Config) -> Result<Self> {
        let http = reqwest::Client::builder()
            .user_agent(format!("{CLIENT_NAME}/{CLIENT_VERSION}"))
            .build()?;
        let device_id = Uuid::new_v4().to_string();

        let auth_header = format!(
            "MediaBrowser Client=\"{CLIENT_NAME}\", Device=\"{DEVICE_NAME}\", DeviceId=\"{device_id}\", Version=\"{CLIENT_VERSION}\""
        );

        let url = format!("{}/Users/AuthenticateByName", cfg.server);
        let resp = http
            .post(&url)
            .header("X-Emby-Authorization", &auth_header)
            .json(&AuthRequest {
                username: &cfg.user,
                pw: &cfg.password,
            })
            .send()
            .await
            .with_context(|| format!("POST {url}"))?;

        let status = resp.status();
        if !status.is_success() {
            let body = resp.text().await.unwrap_or_default();
            return Err(anyhow!("authentication failed: HTTP {status}: {body}"));
        }
        let parsed: AuthResponse = resp.json().await.context("parsing auth response")?;

        Ok(Self {
            http,
            server: cfg.server.clone(),
            user_id: parsed.user.id,
            user_name: parsed.user.name,
            token: parsed.access_token,
            device_id,
        })
    }

    fn headers(&self) -> HeaderMap {
        let mut h = HeaderMap::new();
        h.insert(
            HeaderName::from_static("x-emby-token"),
            HeaderValue::from_str(&self.token).expect("token is ascii"),
        );
        h
    }

    pub async fn views(&self) -> Result<Vec<Item>> {
        let url = format!("{}/Users/{}/Views", self.server, self.user_id);
        let resp: ItemsResponse = self
            .http
            .get(&url)
            .headers(self.headers())
            .send()
            .await?
            .error_for_status()?
            .json()
            .await?;
        Ok(resp.items)
    }

    pub async fn items(&self, parent_id: &str) -> Result<Vec<Item>> {
        let url = format!("{}/Users/{}/Items", self.server, self.user_id);
        let resp: ItemsResponse = self
            .http
            .get(&url)
            .headers(self.headers())
            .query(&[
                ("ParentId", parent_id),
                // ParentIndexNumber+IndexNumber gives correct season/episode order
                // (and season order inside a series); SortName is the fallback for
                // movies, libraries, etc. where index numbers are absent.
                ("SortBy", "ParentIndexNumber,IndexNumber,SortName"),
                ("SortOrder", "Ascending"),
                ("Fields", "ProductionYear,RunTimeTicks,SeriesName,UserData"),
            ])
            .send()
            .await?
            .error_for_status()?
            .json()
            .await?;
        Ok(resp.items)
    }

    /// In-progress items across all libraries (Emby "Continue Watching").
    pub async fn resume_items(&self, limit: u32) -> Result<Vec<Item>> {
        let url = format!("{}/Users/{}/Items/Resume", self.server, self.user_id);
        let limit_s = limit.to_string();
        let resp: ItemsResponse = self
            .http
            .get(&url)
            .headers(self.headers())
            .query(&[
                ("Limit", limit_s.as_str()),
                ("Recursive", "true"),
                ("MediaTypes", "Video"),
                ("Fields", "ProductionYear,RunTimeTicks,SeriesName,UserData"),
            ])
            .send()
            .await?
            .error_for_status()?
            .json()
            .await?;
        Ok(resp.items)
    }

    /// All episodes for a series, in playback order (season, then episode).
    /// Used to build a multi-season playback queue starting from any episode.
    pub async fn series_episodes(&self, series_id: &str) -> Result<Vec<Item>> {
        let url = format!("{}/Shows/{}/Episodes", self.server, series_id);
        let resp: ItemsResponse = self
            .http
            .get(&url)
            .headers(self.headers())
            .query(&[
                ("UserId", self.user_id.as_str()),
                ("Fields", "ProductionYear,RunTimeTicks,SeriesName,UserData"),
            ])
            .send()
            .await?
            .error_for_status()?
            .json()
            .await?;
        Ok(resp.items)
    }

    /// Ask Emby to rescan/refresh a library folder or media folder.
    pub async fn refresh_item(&self, item_id: &str) -> Result<()> {
        let url = format!("{}/Items/{item_id}/Refresh", self.server);
        let resp = self
            .http
            .post(&url)
            .headers(self.headers())
            .query(&[
                ("Recursive", "true"),
                ("ImageRefreshMode", "Default"),
                ("MetadataRefreshMode", "Default"),
                ("ReplaceAllImages", "false"),
                ("ReplaceAllMetadata", "false"),
            ])
            .send()
            .await
            .with_context(|| format!("POST {url}"))?;

        let status = resp.status();
        if !status.is_success() {
            let body = resp.text().await.unwrap_or_default();
            return Err(anyhow!("refresh failed: HTTP {status}: {body}"));
        }
        Ok(())
    }

    pub fn stream_url(&self, item_id: &str) -> String {
        format!(
            "{}/Videos/{}/stream?Static=true&api_key={}&DeviceId={}",
            self.server, item_id, self.token, self.device_id
        )
    }

    /// Build a playback reporter for a specific item. Cheap; reuses the
    /// async HTTP client. Methods are sync — they bridge into the tokio
    /// runtime internally so they can be called from the libmpv event loop.
    pub fn reporter(&self, item_id: String) -> Reporter {
        Reporter {
            http: self.http.clone(),
            server: self.server.clone(),
            token: self.token.clone(),
            item_id,
            play_session_id: Uuid::new_v4().to_string(),
        }
    }
}

/// Reports playback progress back to Emby so Continue Watching reflects
/// what was played in this TUI. Cheap to construct per playback session.
pub struct Reporter {
    http: reqwest::Client,
    server: String,
    token: String,
    item_id: String,
    play_session_id: String,
}

#[derive(Debug, Serialize)]
struct StartBody<'a> {
    #[serde(rename = "ItemId")]
    item_id: &'a str,
    #[serde(rename = "MediaSourceId")]
    media_source_id: &'a str,
    #[serde(rename = "PlaySessionId")]
    play_session_id: &'a str,
    #[serde(rename = "PlayMethod")]
    play_method: &'static str,
    #[serde(rename = "CanSeek")]
    can_seek: bool,
    #[serde(rename = "PositionTicks")]
    position_ticks: i64,
}

#[derive(Debug, Serialize)]
struct ProgressBody<'a> {
    #[serde(rename = "ItemId")]
    item_id: &'a str,
    #[serde(rename = "MediaSourceId")]
    media_source_id: &'a str,
    #[serde(rename = "PlaySessionId")]
    play_session_id: &'a str,
    #[serde(rename = "PlayMethod")]
    play_method: &'static str,
    #[serde(rename = "PositionTicks")]
    position_ticks: i64,
    #[serde(rename = "IsPaused")]
    is_paused: bool,
    #[serde(rename = "EventName")]
    event_name: &'static str,
}

#[derive(Debug, Serialize)]
struct StoppedBody<'a> {
    #[serde(rename = "ItemId")]
    item_id: &'a str,
    #[serde(rename = "MediaSourceId")]
    media_source_id: &'a str,
    #[serde(rename = "PlaySessionId")]
    play_session_id: &'a str,
    #[serde(rename = "PositionTicks")]
    position_ticks: i64,
}

impl Reporter {
    async fn post_async<T: Serialize>(&self, path: &str, body: &T) -> Result<()> {
        let url = format!("{}{path}", self.server);
        let resp = self
            .http
            .post(&url)
            .header("X-Emby-Token", &self.token)
            .json(body)
            .send()
            .await
            .with_context(|| format!("POST {url}"))?;
        if !resp.status().is_success() {
            return Err(anyhow!("Emby reporting failed: HTTP {}", resp.status()));
        }
        Ok(())
    }

    /// Bridge from the sync libmpv event loop into the async runtime.
    /// Requires being called from a thread that participates in a
    /// multi-thread tokio runtime (true when invoked from `#[tokio::main]`).
    fn post<T: Serialize>(&self, path: &str, body: &T) -> Result<()> {
        tokio::task::block_in_place(|| {
            tokio::runtime::Handle::current().block_on(self.post_async(path, body))
        })
    }

    pub fn started(&self, position_ticks: i64) -> Result<()> {
        self.post(
            "/Sessions/Playing",
            &StartBody {
                item_id: &self.item_id,
                media_source_id: &self.item_id,
                play_session_id: &self.play_session_id,
                play_method: "DirectStream",
                can_seek: true,
                position_ticks,
            },
        )
    }

    pub fn progress(&self, position_ticks: i64, is_paused: bool) -> Result<()> {
        self.post(
            "/Sessions/Playing/Progress",
            &ProgressBody {
                item_id: &self.item_id,
                media_source_id: &self.item_id,
                play_session_id: &self.play_session_id,
                play_method: "DirectStream",
                position_ticks,
                is_paused,
                event_name: "TimeUpdate",
            },
        )
    }

    pub fn stopped(&self, position_ticks: i64) -> Result<()> {
        self.post(
            "/Sessions/Playing/Stopped",
            &StoppedBody {
                item_id: &self.item_id,
                media_source_id: &self.item_id,
                play_session_id: &self.play_session_id,
                position_ticks,
            },
        )
    }
}