use actix_web::web::Data;
use actix_web::{get, web, HttpRequest, HttpResponse, Responder};
use chrono::LocalResult::{Ambiguous, Single};
use chrono::{DateTime, Datelike, FixedOffset, Local, LocalResult, NaiveDate, TimeZone, Utc};
use log::{debug, trace, warn};
use opentelemetry::trace::{Span, Status, Tracer};
use opentelemetry::KeyValue;
use rayon::prelude::*;
use serde::{Deserialize, Serialize};
use std::path::Path;
use std::path::PathBuf;
use walkdir::WalkDir;

use crate::data::Claims;
use crate::files::is_image_or_video;
use crate::otel::{extract_context_from_request, global_tracer};
use crate::state::AppState;

#[derive(Copy, Clone, Deserialize, PartialEq, Debug)]
#[serde(rename_all = "lowercase")]
pub enum MemoriesSpan {
    Day,
    Week,
    Month,
}

#[derive(Deserialize)]
pub struct MemoriesRequest {
    pub span: Option<MemoriesSpan>,
    /// Client timezone offset in minutes from UTC (e.g., -480 for PST, 60 for CET)
    pub timezone_offset_minutes: Option<i32>,
}

#[derive(Debug, Serialize, Clone)]
pub struct MemoryItem {
    pub path: String,
    pub created: Option<i64>,
    pub modified: Option<i64>,
}

#[derive(Debug, Serialize)]
pub struct MemoriesResponse {
    pub items: Vec<MemoryItem>,
}

fn get_file_date_info(
    path: &Path,
    client_timezone: &Option<FixedOffset>,
) -> Option<(NaiveDate, Option<i64>, Option<i64>)> {
    // Read file metadata once
    let meta = std::fs::metadata(path).ok()?;

    // Extract metadata timestamps
    let metadata_created = meta.created().ok().map(|t| {
        let utc: DateTime<Utc> = t.into();
        if let Some(tz) = client_timezone {
            utc.with_timezone(tz).timestamp()
        } else {
            utc.timestamp()
        }
    });

    let metadata_modified = meta.modified().ok().map(|t| {
        let utc: DateTime<Utc> = t.into();
        if let Some(tz) = client_timezone {
            utc.with_timezone(tz).timestamp()
        } else {
            utc.timestamp()
        }
    });

    // Try to get date from filename
    if let Some(date_time) = path
        .file_name()
        .and_then(|filename| filename.to_str())
        .and_then(extract_date_from_filename)
    {
        // Convert to client timezone if specified
        let date_in_timezone = if let Some(tz) = client_timezone {
            date_time.with_timezone(tz)
        } else {
            date_time.with_timezone(&Local).fixed_offset()
        };

        // Use the timestamp from the filename date
        let created_ts = date_in_timezone.timestamp();

        debug!(
            "File date from file {:?} > {:?} = {:?}",
            path.file_name(),
            date_time,
            date_in_timezone
        );
        return Some((
            date_in_timezone.date_naive(),
            Some(created_ts),
            metadata_modified,
        ));
    }

    // Fall back to metadata if no date in filename
    let system_time = meta.created().ok().or_else(|| meta.modified().ok())?;
    let dt_utc: DateTime<Utc> = system_time.into();

    let date_in_timezone = if let Some(tz) = client_timezone {
        dt_utc.with_timezone(tz).date_naive()
    } else {
        dt_utc.with_timezone(&Local).date_naive()
    };

    trace!("Fallback metadata create date = {:?}", date_in_timezone);
    Some((date_in_timezone, metadata_created, metadata_modified))
}

fn extract_date_from_filename(filename: &str) -> Option<DateTime<FixedOffset>> {
    let build_date_from_ymd_capture =
        |captures: &regex::Captures| -> Option<DateTime<FixedOffset>> {
            let year = captures.get(1)?.as_str().parse::<i32>().ok()?;
            let month = captures.get(2)?.as_str().parse::<u32>().ok()?;
            let day = captures.get(3)?.as_str().parse::<u32>().ok()?;
            let hour = captures.get(4)?.as_str().parse::<u32>().ok()?;
            let min = captures.get(5)?.as_str().parse::<u32>().ok()?;
            let sec = captures.get(6)?.as_str().parse::<u32>().ok()?;

            match Local.from_local_datetime(
                &NaiveDate::from_ymd_opt(year, month, day)?.and_hms_opt(hour, min, sec)?,
            ) {
                Single(dt) => Some(dt.fixed_offset()),
                Ambiguous(early_dt, _) => Some(early_dt.fixed_offset()),
                LocalResult::None => {
                    warn!("Weird local date: {:?}", filename);
                    None
                }
            }
        };

    // 1. Screenshot format: Screenshot_2014-06-01-20-44-50.png
    if let Some(captures) =
        regex::Regex::new(r"Screenshot_(\d{4})-(\d{2})-(\d{2})-(\d{2})-(\d{2})-(\d{2})")
            .ok()?
            .captures(filename)
            .and_then(|c| build_date_from_ymd_capture(&c))
    {
        return Some(captures);
    }

    // 2. Dash format: 2015-01-09_02-15-15.jpg
    if let Some(captures) = regex::Regex::new(r"(\d{4})-(\d{2})-(\d{2})_(\d{2})-(\d{2})-(\d{2})")
        .ok()?
        .captures(filename)
        .and_then(|c| build_date_from_ymd_capture(&c))
    {
        return Some(captures);
    }

    // 3. Compact format: 20140927101712.jpg
    if let Some(captures) = regex::Regex::new(r"(\d{4})(\d{2})(\d{2})(\d{2})(\d{2})(\d{2})")
        .ok()?
        .captures(filename)
        .and_then(|c| build_date_from_ymd_capture(&c))
    {
        return Some(captures);
    }

    // 4. Timestamp format: 1401638400.jpeg
    if let Some(captures) = regex::Regex::new(r"(\d{10}|\d{13})\.")
        .ok()?
        .captures(filename)
    {
        let timestamp_str = captures.get(1)?.as_str();

        // Millisecond timestamp (13 digits)
        if timestamp_str.len() >= 13 {
            if let Some(date_time) = timestamp_str[0..13]
                .parse::<i64>()
                .ok()
                .and_then(|timestamp_millis| DateTime::from_timestamp_millis(timestamp_millis))
                .map(|naive_dt| naive_dt.fixed_offset())
            {
                return Some(date_time);
            }
        }

        // Second timestamp (10 digits)
        if timestamp_str.len() >= 10 {
            if let Some(date_time) = timestamp_str[0..10]
                .parse::<i64>()
                .ok()
                .and_then(|timestamp_secs| DateTime::from_timestamp(timestamp_secs, 0))
                .map(|naive_dt| naive_dt.fixed_offset())
            {
                return Some(date_time);
            }
        }
    }

    None
}

#[get("/memories")]
pub async fn list_memories(
    _claims: Claims,
    request: HttpRequest,
    q: web::Query<MemoriesRequest>,
    app_state: Data<AppState>,
) -> impl Responder {
    let tracer = global_tracer();
    let context = extract_context_from_request(&request);
    let mut span = tracer.start_with_context("list_memories", &context);

    let span_mode = q.span.unwrap_or(MemoriesSpan::Day);
    let years_back: u32 = 15;

    // Create timezone from client offset, default to local timezone if not provided
    let client_timezone = match q.timezone_offset_minutes {
        Some(offset_mins) => {
            let offset_secs = offset_mins * 60;
            Some(
                FixedOffset::east_opt(offset_secs)
                    .unwrap_or_else(|| FixedOffset::east_opt(0).unwrap()),
            )
        }
        None => None,
    };

    let now = if let Some(tz) = client_timezone {
        debug!("Client timezone: {:?}", tz);
        Utc::now().with_timezone(&tz).date_naive()
    } else {
        Local::now().date_naive()
    };

    debug!("Now: {:?}", now);

    let base = Path::new(&app_state.base_path);

    // Build a list of excluded directories with full paths
    let excluded_paths: Vec<PathBuf> = app_state
        .excluded_dirs
        .iter()
        .map(|dir| base.join(dir))
        .collect();

    debug!("Excluded directories: {:?}", excluded_paths);

    let entries: Vec<_> = WalkDir::new(base)
        .into_iter()
        .filter_map(|e| e.ok())
        .filter(|e| {
            // Skip excluded directories
            if !excluded_paths.is_empty() {
                let path = e.path();
                for excluded in &excluded_paths {
                    if path.starts_with(excluded) {
                        debug!("Skipping excluded path: {:?}", path);
                        return false;
                    }
                }
            }

            true
        })
        .filter(|e| e.file_type().is_file() && is_image_or_video(e.path()))
        .collect();

    let mut memories_with_dates: Vec<(MemoryItem, NaiveDate)> = entries
        .par_iter()
        .filter_map(|entry| {
            let path = entry.path();

            // Get file date and timestamps in one operation
            let (file_date, created, modified) = match get_file_date_info(path, &client_timezone) {
                Some(info) => info,
                None => {
                    warn!("No date info found for file: {:?}", path);
                    return None;
                }
            };

            if is_memories_match(file_date, now, span_mode, years_back) {
                return if let Ok(rel) = path.strip_prefix(base) {
                    Some((
                        MemoryItem {
                            path: rel.to_string_lossy().to_string(),
                            created,
                            modified,
                        },
                        file_date,
                    ))
                } else {
                    warn!("Failed to strip prefix from path: {:?}", path);
                    None
                };
            }

            None
        })
        .collect();

    match span_mode {
        // Sort by absolute time for a more 'overview'
        MemoriesSpan::Month => memories_with_dates.sort_by(|a, b| a.1.cmp(&b.1)),
        _ => {
            memories_with_dates.sort_by(|a, b| {
                let day_comparison = a.1.day().cmp(&b.1.day());

                if day_comparison == std::cmp::Ordering::Equal {
                    match (a.0.created, b.0.created) {
                        (Some(a_time), Some(b_time)) => a_time.cmp(&b_time),
                        (Some(_), None) => std::cmp::Ordering::Less,
                        (None, Some(_)) => std::cmp::Ordering::Greater,
                        (None, None) => std::cmp::Ordering::Equal,
                    }
                } else {
                    day_comparison
                }
            });
        }
    }
    // Sort by day of the month and time (using the created timestamp)

    let items: Vec<MemoryItem> = memories_with_dates.into_iter().map(|(m, _)| m).collect();

    span.add_event(
        "memories_scanned",
        vec![
            KeyValue::new("span", format!("{:?}", span_mode)),
            KeyValue::new("years_back", years_back.to_string()),
            KeyValue::new("result_count", items.len().to_string()),
            KeyValue::new(
                "client_timezone",
                format!(
                    "{:?}",
                    client_timezone.unwrap_or_else(|| FixedOffset::east_opt(0).unwrap())
                ),
            ),
            KeyValue::new("excluded_dirs", format!("{:?}", app_state.excluded_dirs)),
        ],
    );
    span.set_status(Status::Ok);

    HttpResponse::Ok().json(MemoriesResponse { items })
}

fn is_memories_match(
    file_date: NaiveDate,
    today: NaiveDate,
    span: MemoriesSpan,
    years_back: u32,
) -> bool {
    if file_date > today {
        return false;
    }
    let years_diff = (today.year() - file_date.year()).unsigned_abs();
    if years_diff > years_back {
        warn!(
            "File date is too far in the past: {:?} vs {:?}",
            file_date, today
        );
        return false;
    }

    match span {
        MemoriesSpan::Day => same_month_day_any_year(file_date, today),
        MemoriesSpan::Week => same_week_any_year(file_date, today),
        MemoriesSpan::Month => same_month_any_year(file_date, today),
    }
}

fn same_month_day_any_year(a: NaiveDate, b: NaiveDate) -> bool {
    a.month() == b.month() && a.day() == b.day()
}

// Match same ISO week number and same weekday (ignoring year)
fn same_week_any_year(a: NaiveDate, b: NaiveDate) -> bool {
    a.iso_week().week().eq(&b.iso_week().week())
}

// Match same month (ignoring day and year)
fn same_month_any_year(a: NaiveDate, b: NaiveDate) -> bool {
    a.month() == b.month()
}

#[cfg(test)]
mod tests {
    use super::*;
    use chrono::Timelike;
    use std::fs::File;
    use tempfile::tempdir;

    // Add new tests for our date extraction functionality

    #[test]
    fn test_extract_date_from_filename_screenshot_format() {
        let filename = "Screenshot_2014-06-01-20-44-50.png";
        let date_time = extract_date_from_filename(filename).unwrap();

        assert_eq!(date_time.year(), 2014);
        assert_eq!(date_time.month(), 6);
        assert_eq!(date_time.day(), 1);
        assert_eq!(date_time.hour(), 20);
        assert_eq!(date_time.minute(), 44);
        assert_eq!(date_time.second(), 50);
    }

    #[test]
    fn test_extract_date_from_filename_dash_format() {
        let filename = "2015-01-09_02-15-15.jpg";
        let date_time = extract_date_from_filename(filename).unwrap();

        assert_eq!(date_time.year(), 2015);
        assert_eq!(date_time.month(), 1);
        assert_eq!(date_time.day(), 9);
        assert_eq!(date_time.hour(), 2);
        assert_eq!(date_time.minute(), 15);
        assert_eq!(date_time.second(), 15);
    }

    #[test]
    fn test_extract_date_from_filename_compact_format() {
        let filename = "20140927101712.jpg";
        let date_time = extract_date_from_filename(filename).unwrap();

        assert_eq!(date_time.year(), 2014);
        assert_eq!(date_time.month(), 9);
        assert_eq!(date_time.day(), 27);
        assert_eq!(date_time.hour(), 10);
        assert_eq!(date_time.minute(), 17);
        assert_eq!(date_time.second(), 12);
    }

    #[test]
    fn test_extract_date_from_filename_timestamp_format() {
        let filename = "xyz_1401638400.jpeg"; // Unix timestamp for 2014-06-01 16:00:00 UTC
                                              // Timestamps are already in UTC, so timezone doesn't matter for this test
        let date_time = extract_date_from_filename(filename).unwrap();

        assert_eq!(date_time.year(), 2014);
        assert_eq!(date_time.month(), 6);
        assert_eq!(date_time.day(), 1);
        assert_eq!(date_time.hour(), 16);
        assert_eq!(date_time.minute(), 0);
        assert_eq!(date_time.second(), 0);
    }

    #[test]
    fn test_extract_date_from_filename_timestamp_millis_format() {
        let filename = "xyz_1401638400000.jpeg"; // Unix timestamp in milliseconds
        let date_time = extract_date_from_filename(filename).unwrap();

        assert_eq!(date_time.year(), 2014);
        assert_eq!(date_time.month(), 6);
        assert_eq!(date_time.day(), 1);
        assert_eq!(date_time.hour(), 16);
        assert_eq!(date_time.minute(), 0);
        assert_eq!(date_time.second(), 0);
    }

    #[test]
    fn test_get_file_date_info_from_filename() {
        let temp_dir = tempdir().unwrap();
        let temp_file = temp_dir.path().join("Screenshot_2014-06-01-20-44-50.png");
        File::create(&temp_file).unwrap();

        let (date, created, _) =
            get_file_date_info(&temp_file, &Some(*Local::now().fixed_offset().offset())).unwrap();

        // Check that date is from filename
        assert_eq!(date.year(), 2014);
        assert_eq!(date.month(), 6);
        assert_eq!(date.day(), 1);

        // Check that created timestamp matches the date from filename
        assert!(created.is_some());
        let ts = created.unwrap();
        // The timestamp should be for 2014-06-01 20:44:50 in the LOCAL timezone
        let dt_from_ts = Local.timestamp_opt(ts, 0).unwrap();
        assert_eq!(dt_from_ts.year(), 2014);
        assert_eq!(dt_from_ts.month(), 6);
        assert_eq!(dt_from_ts.day(), 1);
        assert_eq!(dt_from_ts.hour(), 20);
        assert_eq!(dt_from_ts.minute(), 44);
        assert_eq!(dt_from_ts.second(), 50);
    }

    #[test]
    fn test_get_file_date_info_from_metadata() {
        let temp_dir = tempdir().unwrap();
        let temp_file = temp_dir.path().join("regular_image.jpg");
        File::create(&temp_file).unwrap();

        let (date, created, modified) = get_file_date_info(&temp_file, &None).unwrap();

        // Both date and timestamps should be from metadata (recent)
        let today = Local::now().date_naive();
        assert_eq!(date.year(), today.year());
        assert_eq!(date.month(), today.month());

        // Both timestamps should be valid
        assert!(created.is_some());
        assert!(modified.is_some());

        // Check that timestamps are recent
        let dt_created = DateTime::<Utc>::from_timestamp(created.unwrap(), 0).unwrap();
        assert_eq!(dt_created.year(), today.year());

        let dt_modified = DateTime::<Utc>::from_timestamp(modified.unwrap(), 0).unwrap();
        assert_eq!(dt_modified.year(), today.year());
    }
}