use crate::{
    db::Pool,
    error::{AppError, AppResult},
    models::objective::{
        ClaimRewardResult, ObjectiveDefinition, ObjectiveProgress, ObjectiveWithProgress,
    },
};
use anyhow::Context;
use sqlx::{Sqlite, Transaction};
use std::path::Path;
use uuid::Uuid;

pub fn load_objective_definitions(data_dir: &str) -> anyhow::Result<Vec<ObjectiveDefinition>> {
    let dir = Path::new(data_dir).join("objectives");
    let mut defs = Vec::new();
    if !dir.exists() {
        return Ok(defs);
    }
    for entry in std::fs::read_dir(&dir)? {
        let entry = entry?;
        let path = entry.path();
        if path.extension().map(|e| e == "json").unwrap_or(false) {
            let content =
                std::fs::read_to_string(&path).with_context(|| format!("reading {:?}", path))?;
            let batch: Vec<ObjectiveDefinition> =
                serde_json::from_str(&content).with_context(|| format!("parsing {:?}", path))?;
            defs.extend(batch);
        }
    }
    Ok(defs)
}

pub async fn get_objectives_with_progress(
    pool: &Pool,
    profile_id: &str,
    defs: &[ObjectiveDefinition],
) -> AppResult<Vec<ObjectiveWithProgress>> {
    let progress_rows = sqlx::query_as::<_, ObjectiveProgress>(
        "SELECT id, profile_id, objective_id, current, completed, claimed, updated_at FROM objective_progress WHERE profile_id = ?"
    )
    .bind(profile_id)
    .fetch_all(pool)
    .await?;

    let result = defs
        .iter()
        .map(|def| {
            let prog = progress_rows.iter().find(|p| p.objective_id == def.id);
            ObjectiveWithProgress {
                definition: def.clone(),
                current: prog.map(|p| p.current).unwrap_or(0),
                completed: prog.map(|p| p.completed).unwrap_or(false),
                claimed: prog.map(|p| p.claimed).unwrap_or(false),
            }
        })
        .collect();

    Ok(result)
}

/// Increment a metric for all objectives that track it.
pub async fn increment_metric(
    pool: &Pool,
    profile_id: &str,
    defs: &[ObjectiveDefinition],
    metric: &str,
    amount: i64,
) -> AppResult<Vec<String>> {
    let mut completed_ids = Vec::new();

    for def in defs.iter().filter(|d| d.metric.as_str() == metric) {
        let existing = sqlx::query_as::<_, ObjectiveProgress>(
            "SELECT id, profile_id, objective_id, current, completed, claimed, updated_at FROM objective_progress WHERE profile_id = ? AND objective_id = ?"
        )
        .bind(profile_id)
        .bind(&def.id)
        .fetch_optional(pool)
        .await?;

        let now = chrono::Utc::now().to_rfc3339();

        if let Some(prog) = existing {
            if prog.completed {
                continue;
            }
            let new_val = (prog.current + amount).min(def.target);
            let now_complete = new_val >= def.target;
            sqlx::query(
                "UPDATE objective_progress SET current = ?, completed = ?, updated_at = ? WHERE id = ?"
            )
            .bind(new_val)
            .bind(now_complete)
            .bind(&now)
            .bind(&prog.id)
            .execute(pool)
            .await?;
            if now_complete {
                completed_ids.push(def.id.clone());
            }
        } else {
            let new_val = amount.min(def.target);
            let now_complete = new_val >= def.target;
            let id = Uuid::new_v4().to_string();
            sqlx::query(
                "INSERT INTO objective_progress (id, profile_id, objective_id, current, completed, claimed, updated_at) VALUES (?, ?, ?, ?, ?, 0, ?)"
            )
            .bind(&id)
            .bind(profile_id)
            .bind(&def.id)
            .bind(new_val)
            .bind(now_complete)
            .bind(&now)
            .execute(pool)
            .await?;
            if now_complete {
                completed_ids.push(def.id.clone());
            }
        }
    }

    Ok(completed_ids)
}

/// Transaction-scoped [`increment_metric`] for the atomic match-completion path.
/// Same semantics, but every read/write runs inside the caller's transaction so
/// objective progress commits (or rolls back) together with the coins, XP, and
/// statistics of the same match. `now` is threaded so one match stamps a single
/// timestamp.
pub async fn increment_metric_tx(
    tx: &mut Transaction<'_, Sqlite>,
    profile_id: &str,
    defs: &[ObjectiveDefinition],
    metric: &str,
    amount: i64,
    now: &str,
) -> AppResult<Vec<String>> {
    let mut completed_ids = Vec::new();

    for def in defs.iter().filter(|d| d.metric.as_str() == metric) {
        let existing = sqlx::query_as::<_, ObjectiveProgress>(
            "SELECT id, profile_id, objective_id, current, completed, claimed, updated_at FROM objective_progress WHERE profile_id = ? AND objective_id = ?"
        )
        .bind(profile_id)
        .bind(&def.id)
        .fetch_optional(&mut **tx)
        .await?;

        if let Some(prog) = existing {
            if prog.completed {
                continue;
            }
            let new_val = (prog.current + amount).min(def.target);
            let now_complete = new_val >= def.target;
            sqlx::query(
                "UPDATE objective_progress SET current = ?, completed = ?, updated_at = ? WHERE id = ?"
            )
            .bind(new_val)
            .bind(now_complete)
            .bind(now)
            .bind(&prog.id)
            .execute(&mut **tx)
            .await?;
            if now_complete {
                completed_ids.push(def.id.clone());
            }
        } else {
            let new_val = amount.min(def.target);
            let now_complete = new_val >= def.target;
            let id = Uuid::new_v4().to_string();
            sqlx::query(
                "INSERT INTO objective_progress (id, profile_id, objective_id, current, completed, claimed, updated_at) VALUES (?, ?, ?, ?, ?, 0, ?)"
            )
            .bind(&id)
            .bind(profile_id)
            .bind(&def.id)
            .bind(new_val)
            .bind(now_complete)
            .bind(now)
            .execute(&mut **tx)
            .await?;
            if now_complete {
                completed_ids.push(def.id.clone());
            }
        }
    }

    Ok(completed_ids)
}

pub async fn claim_objective(
    pool: &Pool,
    profile_id: &str,
    club_id: &str,
    defs: &[ObjectiveDefinition],
    objective_id: &str,
) -> AppResult<ClaimRewardResult> {
    let prog = sqlx::query_as::<_, ObjectiveProgress>(
        "SELECT id, profile_id, objective_id, current, completed, claimed, updated_at FROM objective_progress WHERE profile_id = ? AND objective_id = ?"
    )
    .bind(profile_id)
    .bind(objective_id)
    .fetch_optional(pool)
    .await?
    .ok_or_else(|| AppError::NotFound("objective not started yet".into()))?;

    if !prog.completed {
        return Err(AppError::BadRequest("objective not completed yet".into()));
    }
    if prog.claimed {
        return Err(AppError::Conflict("reward already claimed".into()));
    }

    let def = defs
        .iter()
        .find(|d| d.id == objective_id)
        .ok_or_else(|| AppError::NotFound(format!("objective '{objective_id}' not found")))?;

    sqlx::query("UPDATE objective_progress SET claimed = 1 WHERE id = ?")
        .bind(&prog.id)
        .execute(pool)
        .await?;

    if def.reward_coins > 0 {
        crate::services::club::add_coins(pool, club_id, def.reward_coins).await?;
    }
    if def.reward_xp > 0 {
        crate::services::profile::add_xp(pool, profile_id, def.reward_xp).await?;
    }
    if let Some(pack_id) = &def.reward_pack_id {
        crate::services::pack::grant_pack(pool, club_id, pack_id).await?;
    }

    Ok(ClaimRewardResult {
        objective_id: objective_id.to_string(),
        coins_granted: def.reward_coins,
        xp_granted: def.reward_xp,
        pack_granted: def.reward_pack_id.clone(),
    })
}