use application::ports::{
    ActivityFeedPageData, BlockedActorEntry, BlockedActorsPageData, BlockedDomainEntry,
    BlockedDomainsPageData, FollowersPageData, FollowingPageData, HtmlPageContext, HtmlRenderer,
    ImportMappingPageData, ImportPreviewPageData, ImportPreviewRow, ImportProfileView,
    ImportRowStatus, ImportUploadPageData, LoginPageData, MovieDetailPageData, NewReviewPageData,
    ProfilePageData, ProfileSettingsPageData, RegisterPageData, UsersPageData, WatchlistPageData,
};
use askama::Template;
use chrono::Datelike;
use domain::models::{
    DiaryEntry, FeedEntry, MonthActivity, MonthlyRating, ReviewSource, UserStats, UserTrends,
    collections::Paginated,
};

mod filters {
    #[askama::filter_fn]
    pub fn poster_src<T: std::fmt::Display>(
        path: T,
        _env: &dyn askama::Values,
    ) -> askama::Result<String> {
        let p = path.to_string();
        if p.starts_with("http://") || p.starts_with("https://") {
            Ok(p)
        } else {
            Ok(format!("/images/{}", p))
        }
    }
}

struct PageItem {
    number: u32,
    is_current: bool,
    is_ellipsis: bool,
}

fn build_page_items(total_pages: u32, current_page: u32) -> Vec<PageItem> {
    if total_pages <= 1 {
        return vec![];
    }
    let mut set = std::collections::BTreeSet::new();
    set.insert(0u32);
    set.insert(total_pages - 1);
    let start = current_page.saturating_sub(2);
    let end = (current_page + 2).min(total_pages - 1);
    for p in start..=end {
        set.insert(p);
    }
    let pages: Vec<u32> = set.into_iter().collect();
    let mut items = Vec::new();
    for (i, &p) in pages.iter().enumerate() {
        if i > 0 && p > pages[i - 1] + 1 {
            items.push(PageItem {
                number: 0,
                is_current: false,
                is_ellipsis: true,
            });
        }
        items.push(PageItem {
            number: p,
            is_current: p == current_page,
            is_ellipsis: false,
        });
    }
    items
}

#[derive(Template)]
#[template(path = "diary.html")]
struct DiaryTemplate<'a> {
    entries: &'a [DiaryEntry],
    current_offset: u32,
    limit: u32,
    has_more: bool,
    ctx: &'a HtmlPageContext,
    page_items: Vec<PageItem>,
}

#[derive(Template)]
#[template(path = "login.html")]
struct LoginTemplate<'a> {
    error: Option<&'a str>,
    ctx: &'a HtmlPageContext,
}

#[derive(Template)]
#[template(path = "register.html")]
struct RegisterTemplate<'a> {
    error: Option<&'a str>,
    ctx: &'a HtmlPageContext,
}

#[derive(Template)]
#[template(path = "new_review.html")]
struct NewReviewTemplate<'a> {
    error: Option<&'a str>,
    ctx: &'a HtmlPageContext,
}

#[derive(Template)]
#[template(path = "activity_feed.html")]
struct ActivityFeedTemplate<'a> {
    entries: &'a [FeedEntry],
    current_offset: u32,
    limit: u32,
    has_more: bool,
    ctx: &'a HtmlPageContext,
    page_items: Vec<PageItem>,
    pub filter: String,
    pub sort_by: String,
    pub search: String,
}

#[derive(Template)]
#[template(path = "movie_detail.html")]
struct MovieDetailTemplate<'a> {
    ctx: &'a HtmlPageContext,
    movie: &'a domain::models::Movie,
    stats: &'a domain::models::MovieStats,
    profile: Option<&'a domain::models::MovieProfile>,
    reviews: &'a [domain::models::FeedEntry],
    on_watchlist: bool,
    current_offset: u32,
    has_more: bool,
    limit: u32,
    histogram_max: u64,
}

#[derive(Template)]
#[template(path = "watchlist.html")]
struct WatchlistTemplate<'a> {
    ctx: &'a HtmlPageContext,
    owner_id: uuid::Uuid,
    display_entries: &'a [application::ports::WatchlistDisplayEntry],
    current_offset: u32,
    has_more: bool,
    limit: u32,
    is_owner: bool,
    error: Option<String>,
}

impl<'a> ActivityFeedTemplate<'a> {
    pub fn filter_qs(&self) -> String {
        let mut parts = vec![
            format!("filter={}", self.filter),
            format!("sort_by={}", self.sort_by),
        ];
        if !self.search.is_empty() {
            let encoded = self
                .search
                .replace(' ', "+")
                .replace('#', "%23")
                .replace('&', "%26")
                .replace('=', "%3D");
            parts.push(format!("search={}", encoded));
        }
        format!("&{}", parts.join("&"))
    }
}

pub struct RemoteActorDisplay {
    pub handle: String,
    pub display_name: String,
    pub initial: char,
    pub url: String,
}

struct UserSummaryView {
    user_id: uuid::Uuid,
    display_name: String,
    initial: char,
    avg_rating_display: String,
    total_movies: i64,
    avatar_url: Option<String>,
}

#[derive(Template)]
#[template(path = "users.html")]
struct UsersTemplate<'a> {
    users: Vec<UserSummaryView>,
    ctx: &'a HtmlPageContext,
    remote_actors: Vec<RemoteActorDisplay>,
}

struct MonthlyRatingRow<'a> {
    rating: &'a MonthlyRating,
    bar_height_px: i64,
}

#[derive(Template)]
#[template(path = "profile.html")]
struct ProfileTemplate<'a> {
    ctx: &'a HtmlPageContext,
    profile_display_name: String,
    profile_user_id: uuid::Uuid,
    stats: &'a UserStats,
    avg_rating_display: String,
    favorite_director_display: String,
    most_active_month_display: String,
    view: &'a str,
    entries: Option<&'a Paginated<DiaryEntry>>,
    current_offset: u32,
    has_more: bool,
    limit: u32,
    history: Option<&'a Vec<MonthActivity>>,
    trends: Option<&'a UserTrends>,
    monthly_rating_rows: Vec<MonthlyRatingRow<'a>>,
    heatmap: Vec<HeatmapCell>,
    page_items: Vec<PageItem>,
    is_own_profile: bool,
    error: Option<String>,
    following_count: usize,
    followers_count: usize,
    pending_followers: Vec<RemoteActorData>,
    pub sort_by: String,
    pub search: String,
}

impl<'a> ProfileTemplate<'a> {
    pub fn filter_qs(&self) -> String {
        let mut parts = vec![
            format!("view={}", self.view),
            format!("sort_by={}", self.sort_by),
        ];
        if !self.search.is_empty() {
            let encoded = self
                .search
                .replace(' ', "+")
                .replace('#', "%23")
                .replace('&', "%26")
                .replace('=', "%3D");
            parts.push(format!("search={}", encoded));
        }
        format!("&{}", parts.join("&"))
    }
}

struct RemoteActorData {
    handle: String,
    display_name: Option<String>,
    url: String,
    avatar_url: Option<String>,
}

#[derive(Template)]
#[template(path = "following.html")]
struct FollowingTemplate {
    ctx: HtmlPageContext,
    user_id: uuid::Uuid,
    actors: Vec<RemoteActorData>,
    error: Option<String>,
}

#[derive(Template)]
#[template(path = "followers.html")]
struct FollowersTemplate {
    ctx: HtmlPageContext,
    user_id: uuid::Uuid,
    actors: Vec<RemoteActorData>,
    error: Option<String>,
}

#[derive(Template)]
#[template(path = "blocked_domains.html")]
struct BlockedDomainsTemplate<'a> {
    ctx: &'a HtmlPageContext,
    domains: &'a [BlockedDomainEntry],
}

#[derive(Template)]
#[template(path = "blocked_actors.html")]
struct BlockedActorsTemplate<'a> {
    ctx: &'a HtmlPageContext,
    actors: &'a [BlockedActorEntry],
}

struct HeatmapCell {
    month_label: String,
    count: i64,
    alpha: f64,
}

#[allow(dead_code)]
fn relative_time(dt: chrono::NaiveDateTime) -> String {
    let now = chrono::Utc::now().naive_utc();
    let diff = now.signed_duration_since(dt);
    if diff.num_seconds() <= 0 {
        return "just now".to_string();
    }
    let minutes = diff.num_minutes();
    let hours = diff.num_hours();
    let days = diff.num_days();
    if minutes < 1 {
        return "just now".to_string();
    }
    if minutes < 60 {
        return format!("{} min ago", minutes);
    }
    if hours < 24 {
        return format!("{} h ago", hours);
    }
    if days == 1 {
        return "yesterday".to_string();
    }
    if days < 30 {
        return format!("{} days ago", days);
    }
    dt.format("%b %-d, %Y").to_string()
}

fn build_heatmap(history: &[MonthActivity]) -> Vec<HeatmapCell> {
    let current_year = chrono::Utc::now().year();
    let count_for = |m: &str| -> i64 {
        history
            .iter()
            .find(|a| a.year_month == format!("{}-{}", current_year, m))
            .map(|a| a.count)
            .unwrap_or(0)
    };
    let months = [
        ("01", "Jan"),
        ("02", "Feb"),
        ("03", "Mar"),
        ("04", "Apr"),
        ("05", "May"),
        ("06", "Jun"),
        ("07", "Jul"),
        ("08", "Aug"),
        ("09", "Sep"),
        ("10", "Oct"),
        ("11", "Nov"),
        ("12", "Dec"),
    ];
    let counts: Vec<i64> = months.iter().map(|(m, _)| count_for(m)).collect();
    let max = counts.iter().copied().max().unwrap_or(0).max(1);
    months
        .iter()
        .zip(counts.iter())
        .map(|((_, label), &count)| {
            let alpha = if count == 0 {
                0.05
            } else {
                0.15 + 0.75 * (count as f64 / max as f64)
            };
            HeatmapCell {
                month_label: label.to_string(),
                count,
                alpha,
            }
        })
        .collect()
}

fn bar_height_px(avg_rating: f64) -> i64 {
    (avg_rating / 5.0 * 60.0) as i64
}

#[derive(Template)]
#[template(path = "profile_settings.html")]
struct ProfileSettingsTemplate<'a> {
    ctx: &'a HtmlPageContext,
    bio: Option<&'a str>,
    avatar_url: Option<&'a str>,
    banner_url: Option<&'a str>,
    also_known_as: Option<&'a str>,
    profile_fields: &'a [(String, String)],
    saved: bool,
}

#[derive(Template)]
#[template(path = "import_upload.html")]
struct ImportUploadTemplate<'a> {
    ctx: &'a HtmlPageContext,
    profiles: &'a [ImportProfileView],
    error: Option<&'a str>,
}

#[derive(Template)]
#[template(path = "import_mapping.html")]
struct ImportMappingTemplate<'a> {
    ctx: &'a HtmlPageContext,
    session_id: &'a str,
    columns: &'a [String],
    sample_rows: &'a [Vec<String>],
    domain_fields: &'a [(&'static str, &'static str)],
    error: Option<&'a str>,
}

#[derive(Template)]
#[template(path = "import_preview.html")]
struct ImportPreviewTemplate<'a> {
    ctx: &'a HtmlPageContext,
    session_id: &'a str,
    columns: &'a [String],
    rows: &'a [ImportPreviewRow],
}

#[derive(Default)]
pub struct AskamaHtmlRenderer;

impl AskamaHtmlRenderer {
    pub fn new() -> Self {
        Self {}
    }
}

impl HtmlRenderer for AskamaHtmlRenderer {
    fn render_diary_page(
        &self,
        data: &Paginated<DiaryEntry>,
        ctx: HtmlPageContext,
    ) -> Result<String, String> {
        let has_more = (data.offset + data.limit) < data.total_count as u32;
        let (total_pages, current_page) = if data.limit > 0 {
            let tp = data.total_count.div_ceil(data.limit as u64) as u32;
            (tp, data.offset / data.limit)
        } else {
            (0, 0)
        };
        DiaryTemplate {
            entries: &data.items,
            current_offset: data.offset,
            limit: data.limit,
            has_more,
            ctx: &ctx,
            page_items: build_page_items(total_pages, current_page),
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_login_page(&self, data: LoginPageData<'_>) -> Result<String, String> {
        LoginTemplate {
            error: data.error,
            ctx: &data.ctx,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_register_page(&self, data: RegisterPageData<'_>) -> Result<String, String> {
        RegisterTemplate {
            error: data.error,
            ctx: &data.ctx,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_new_review_page(&self, data: NewReviewPageData<'_>) -> Result<String, String> {
        NewReviewTemplate {
            error: data.error,
            ctx: &data.ctx,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_activity_feed_page(&self, data: ActivityFeedPageData) -> Result<String, String> {
        let limit = data.limit;
        let total_pages = data.entries.total_count.div_ceil(limit.max(1) as u64) as u32;
        let current_page = data.current_offset.checked_div(limit).unwrap_or(0);
        ActivityFeedTemplate {
            entries: &data.entries.items,
            current_offset: data.current_offset,
            limit,
            has_more: data.has_more,
            ctx: &data.ctx,
            page_items: build_page_items(total_pages, current_page),
            filter: data.filter,
            sort_by: data.sort_by,
            search: data.search,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_users_page(&self, data: UsersPageData) -> Result<String, String> {
        let users: Vec<UserSummaryView> = data
            .users
            .iter()
            .map(|u| {
                let email = u.email();
                let display_name = email.split('@').next().unwrap_or(email).to_string();
                let initial = display_name
                    .chars()
                    .next()
                    .unwrap_or('?')
                    .to_ascii_uppercase();
                let avg_rating_display = u
                    .avg_rating
                    .map(|r| format!("{:.1}", r))
                    .unwrap_or_else(|| "—".to_string());
                UserSummaryView {
                    user_id: u.user_id.value(),
                    display_name,
                    initial,
                    avg_rating_display,
                    total_movies: u.total_movies,
                    avatar_url: u.avatar_path.as_ref().map(|p| format!("/images/{}", p)),
                }
            })
            .collect();
        let remote_actors = data
            .remote_actors
            .into_iter()
            .map(|a| {
                let name = a.display_name.unwrap_or_else(|| a.handle.clone());
                let initial = name.chars().next().unwrap_or('?');
                RemoteActorDisplay {
                    display_name: name,
                    initial,
                    handle: a.handle,
                    url: a.url,
                }
            })
            .collect();
        UsersTemplate {
            users,
            ctx: &data.ctx,
            remote_actors,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_profile_page(&self, data: ProfilePageData) -> Result<String, String> {
        let heatmap = data
            .history
            .as_deref()
            .map(build_heatmap)
            .unwrap_or_default();
        let profile_display_name = data
            .profile_user_email
            .split('@')
            .next()
            .unwrap_or(&data.profile_user_email)
            .to_string();
        let monthly_rating_rows: Vec<MonthlyRatingRow<'_>> = data
            .trends
            .as_ref()
            .map(|t| {
                t.monthly_ratings
                    .iter()
                    .map(|r| MonthlyRatingRow {
                        bar_height_px: bar_height_px(r.avg_rating),
                        rating: r,
                    })
                    .collect()
            })
            .unwrap_or_default();
        let total_pages = data
            .entries
            .as_ref()
            .map(|e| e.total_count.div_ceil(e.limit.max(1) as u64) as u32)
            .unwrap_or(0);
        let current_page = data.current_offset.checked_div(data.limit).unwrap_or(0);
        let avg_rating_display = data
            .stats
            .avg_rating
            .map(|r| format!("{:.1}", r))
            .unwrap_or_else(|| "—".to_string());
        let favorite_director_display = data
            .stats
            .favorite_director
            .as_deref()
            .unwrap_or("—")
            .to_string();
        let most_active_month_display = data
            .stats
            .most_active_month
            .as_deref()
            .unwrap_or("—")
            .to_string();
        ProfileTemplate {
            ctx: &data.ctx,
            profile_display_name,
            profile_user_id: data.profile_user_id,
            stats: &data.stats,
            avg_rating_display,
            favorite_director_display,
            most_active_month_display,
            view: &data.view,
            entries: data.entries.as_ref(),
            current_offset: data.current_offset,
            has_more: data.has_more,
            limit: data.limit,
            history: data.history.as_ref(),
            trends: data.trends.as_ref(),
            monthly_rating_rows,
            heatmap,
            page_items: build_page_items(total_pages, current_page),
            is_own_profile: data.is_own_profile,
            error: data.error,
            following_count: data.following_count,
            followers_count: data.followers_count,
            pending_followers: data
                .pending_followers
                .into_iter()
                .map(|a| RemoteActorData {
                    handle: a.handle,
                    url: a.url,
                    display_name: a.display_name,
                    avatar_url: a.avatar_url,
                })
                .collect(),
            sort_by: data.sort_by.clone(),
            search: data.search.clone(),
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_movie_detail_page(&self, data: MovieDetailPageData) -> Result<String, String> {
        MovieDetailTemplate {
            ctx: &data.ctx,
            movie: &data.movie,
            stats: &data.stats,
            profile: data.profile.as_ref(),
            reviews: &data.reviews.items,
            on_watchlist: data.on_watchlist,
            current_offset: data.current_offset,
            has_more: data.has_more,
            limit: data.limit,
            histogram_max: data.histogram_max,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_watchlist_page(&self, data: WatchlistPageData) -> Result<String, String> {
        WatchlistTemplate {
            ctx: &data.ctx,
            owner_id: data.owner_id,
            display_entries: &data.display_entries,
            current_offset: data.current_offset,
            has_more: data.has_more,
            limit: data.limit,
            is_owner: data.is_owner,
            error: data.error,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_following_page(&self, data: FollowingPageData) -> Result<String, String> {
        FollowingTemplate {
            ctx: data.ctx,
            user_id: data.user_id,
            actors: data
                .actors
                .into_iter()
                .map(|a| RemoteActorData {
                    handle: a.handle,
                    display_name: a.display_name,
                    url: a.url,
                    avatar_url: a.avatar_url,
                })
                .collect(),
            error: data.error,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_followers_page(&self, data: FollowersPageData) -> Result<String, String> {
        FollowersTemplate {
            ctx: data.ctx,
            user_id: data.user_id,
            actors: data
                .actors
                .into_iter()
                .map(|a| RemoteActorData {
                    handle: a.handle,
                    display_name: a.display_name,
                    url: a.url,
                    avatar_url: a.avatar_url,
                })
                .collect(),
            error: data.error,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_import_upload_page(&self, data: ImportUploadPageData) -> Result<String, String> {
        ImportUploadTemplate {
            ctx: &data.ctx,
            profiles: &data.profiles,
            error: data.error.as_deref(),
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_import_mapping_page(&self, data: ImportMappingPageData) -> Result<String, String> {
        ImportMappingTemplate {
            ctx: &data.ctx,
            session_id: &data.session_id,
            columns: &data.columns,
            sample_rows: &data.sample_rows,
            domain_fields: &data.domain_fields,
            error: data.error.as_deref(),
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_import_preview_page(&self, data: ImportPreviewPageData) -> Result<String, String> {
        ImportPreviewTemplate {
            ctx: &data.ctx,
            session_id: &data.session_id,
            columns: &data.columns,
            rows: &data.rows,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_profile_settings_page(
        &self,
        data: ProfileSettingsPageData,
    ) -> Result<String, String> {
        ProfileSettingsTemplate {
            ctx: &data.ctx,
            bio: data.bio.as_deref(),
            avatar_url: data.avatar_url.as_deref(),
            banner_url: data.banner_url.as_deref(),
            also_known_as: data.also_known_as.as_deref(),
            profile_fields: &data.profile_fields,
            saved: data.saved,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_blocked_domains_page(&self, data: BlockedDomainsPageData) -> Result<String, String> {
        BlockedDomainsTemplate {
            ctx: &data.ctx,
            domains: &data.domains,
        }
        .render()
        .map_err(|e| e.to_string())
    }

    fn render_blocked_actors_page(&self, data: BlockedActorsPageData) -> Result<String, String> {
        BlockedActorsTemplate {
            ctx: &data.ctx,
            actors: &data.actors,
        }
        .render()
        .map_err(|e| e.to_string())
    }
}