use diesel::prelude::*;
use diesel::sqlite::SqliteConnection;
use std::ops::DerefMut;
use std::sync::{Arc, Mutex};

use crate::database::models::{
    InsertInsightGenerationJob, InsightGenerationJob, InsightGenerationType, InsightJobStatus,
};
use crate::database::schema;
use crate::database::{DbError, DbErrorKind, connect};
use crate::otel::trace_db_call;

/// Tracks async insight generation jobs. Each call to `create_job` inserts
/// a new row; the application layer prevents concurrent running jobs by
/// cancelling the old one before creating a new one.
pub trait InsightGenerationJobDao: Sync + Send {
    /// Insert a new running job. Always creates a new row (no upsert).
    /// Cleans up terminal-state rows for the same key first.
    fn create_job(
        &mut self,
        context: &opentelemetry::Context,
        library_id: i32,
        file_path: &str,
        generation_type: InsightGenerationType,
    ) -> Result<i32, DbError>;

    /// Mark a job as completed with the resulting insight id. Only updates
    /// if the job is still in "running" status (prevents overwriting a
    /// cancelled job with a late-completing task).
    fn complete_job(
        &mut self,
        context: &opentelemetry::Context,
        job_id: i32,
        insight_id: i32,
    ) -> Result<(), DbError>;

    /// Mark a job as failed with an error message. Only updates if the job
    /// is still in "running" status.
    fn fail_job(
        &mut self,
        context: &opentelemetry::Context,
        job_id: i32,
        error_message: &str,
    ) -> Result<(), DbError>;

    /// Cancel a specific job by id. Only updates if the job is still
    /// in "running" status. Returns true if a row was updated.
    fn cancel_job(
        &mut self,
        context: &opentelemetry::Context,
        job_id: i32,
    ) -> Result<bool, DbError>;

    /// Cancel all running jobs for a given file. Returns the number of
    /// jobs cancelled.
    fn cancel_active_jobs(
        &mut self,
        context: &opentelemetry::Context,
        library_id: i32,
        file_path: &str,
    ) -> Result<usize, DbError>;

    /// Find the latest running job for a given file. Returns None if no
    /// running job exists.
    fn get_active_job(
        &mut self,
        context: &opentelemetry::Context,
        library_id: i32,
        file_path: &str,
    ) -> Result<Option<InsightGenerationJob>, DbError>;

    /// Find any job by id regardless of status.
    fn get_job_by_id(
        &mut self,
        context: &opentelemetry::Context,
        job_id: i32,
    ) -> Result<Option<InsightGenerationJob>, DbError>;

    /// Mark all jobs still in "running" status as "failed" with a recovery
    /// error message. Returns the number of jobs recovered.
    fn recover_orphaned_jobs(&mut self, context: &opentelemetry::Context)
    -> Result<usize, DbError>;
}

pub struct SqliteInsightGenerationJobDao {
    connection: Arc<Mutex<SqliteConnection>>,
}

impl Default for SqliteInsightGenerationJobDao {
    fn default() -> Self {
        Self::new()
    }
}

impl SqliteInsightGenerationJobDao {
    pub fn new() -> Self {
        Self {
            connection: Arc::new(Mutex::new(connect())),
        }
    }

    #[cfg(test)]
    pub fn from_connection(conn: Arc<Mutex<SqliteConnection>>) -> Self {
        Self { connection: conn }
    }
}

impl InsightGenerationJobDao for SqliteInsightGenerationJobDao {
    fn create_job(
        &mut self,
        context: &opentelemetry::Context,
        library_id: i32,
        file_path: &str,
        generation_type: InsightGenerationType,
    ) -> Result<i32, DbError> {
        trace_db_call(context, "insert", "create_job", |_span| {
            use schema::insight_generation_jobs::dsl;

            let mut connection = self
                .connection
                .lock()
                .expect("Unable to lock InsightGenerationJobDao");

            let now = std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("Time went backwards")
                .as_secs() as i64;

            let new_job = InsertInsightGenerationJob {
                library_id,
                path: file_path.to_string(),
                gen_type: generation_type.to_string(),
                status: InsightJobStatus::Running.to_string(),
                started_at: now,
            };

            diesel::insert_into(dsl::insight_generation_jobs)
                .values(&new_job)
                .execute(connection.deref_mut())
                .map_err(|e| anyhow::anyhow!("Failed to insert job: {}", e))?;

            dsl::insight_generation_jobs
                .filter(
                    dsl::library_id
                        .eq(library_id)
                        .and(dsl::file_path.eq(file_path))
                        .and(dsl::generation_type.eq(generation_type.as_str()))
                        .and(dsl::status.eq(InsightJobStatus::Running.as_str())),
                )
                .select(dsl::id)
                .order(dsl::id.desc())
                .first::<i32>(connection.deref_mut())
                .map_err(|e| anyhow::anyhow!("Failed to get job id: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn complete_job(
        &mut self,
        context: &opentelemetry::Context,
        job_id: i32,
        insight_id: i32,
    ) -> Result<(), DbError> {
        trace_db_call(context, "update", "complete_job", |_span| {
            use schema::insight_generation_jobs::dsl;

            let mut connection = self
                .connection
                .lock()
                .expect("Unable to lock InsightGenerationJobDao");

            let now = std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("Time went backwards")
                .as_secs() as i64;

            // Only update if still running — prevents cancelled job from
            // being overwritten by a late-completing task.
            diesel::update(
                dsl::insight_generation_jobs.filter(
                    dsl::id
                        .eq(job_id)
                        .and(dsl::status.eq(InsightJobStatus::Running.as_str())),
                ),
            )
            .set((
                dsl::status.eq(InsightJobStatus::Completed.as_str()),
                dsl::completed_at.eq(Some(now)),
                dsl::result_insight_id.eq(Some(insight_id)),
            ))
            .execute(connection.deref_mut())
            .map(|_| ())
            .map_err(|e| anyhow::anyhow!("Failed to complete job: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
    }

    fn fail_job(
        &mut self,
        context: &opentelemetry::Context,
        job_id: i32,
        error_message: &str,
    ) -> Result<(), DbError> {
        trace_db_call(context, "update", "fail_job", |_span| {
            use schema::insight_generation_jobs::dsl;

            let mut connection = self
                .connection
                .lock()
                .expect("Unable to lock InsightGenerationJobDao");

            let now = std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("Time went backwards")
                .as_secs() as i64;

            // Only update if still running.
            diesel::update(
                dsl::insight_generation_jobs.filter(
                    dsl::id
                        .eq(job_id)
                        .and(dsl::status.eq(InsightJobStatus::Running.as_str())),
                ),
            )
            .set((
                dsl::status.eq(InsightJobStatus::Failed.as_str()),
                dsl::completed_at.eq(Some(now)),
                dsl::error_message.eq(Some(error_message.to_string())),
            ))
            .execute(connection.deref_mut())
            .map(|_| ())
            .map_err(|e| anyhow::anyhow!("Failed to fail job: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
    }

    fn cancel_job(
        &mut self,
        context: &opentelemetry::Context,
        job_id: i32,
    ) -> Result<bool, DbError> {
        trace_db_call(context, "update", "cancel_job", |_span| {
            use schema::insight_generation_jobs::dsl;

            let mut connection = self
                .connection
                .lock()
                .expect("Unable to lock InsightGenerationJobDao");

            let now = std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("Time went backwards")
                .as_secs() as i64;

            let rows = diesel::update(
                dsl::insight_generation_jobs.filter(
                    dsl::id
                        .eq(job_id)
                        .and(dsl::status.eq(InsightJobStatus::Running.as_str())),
                ),
            )
            .set((
                dsl::status.eq(InsightJobStatus::Cancelled.as_str()),
                dsl::completed_at.eq(Some(now)),
                dsl::error_message.eq(Some("cancelled by user".to_string())),
            ))
            .execute(connection.deref_mut())
            .map_err(|e| anyhow::anyhow!("Failed to cancel job: {}", e))?;

            Ok(rows > 0)
        })
        .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
    }

    fn cancel_active_jobs(
        &mut self,
        context: &opentelemetry::Context,
        library_id: i32,
        file_path: &str,
    ) -> Result<usize, DbError> {
        trace_db_call(context, "update", "cancel_active_jobs", |_span| {
            use schema::insight_generation_jobs::dsl;

            let mut connection = self
                .connection
                .lock()
                .expect("Unable to lock InsightGenerationJobDao");

            let now = std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("Time went backwards")
                .as_secs() as i64;

            let rows = diesel::update(
                dsl::insight_generation_jobs.filter(
                    dsl::library_id
                        .eq(library_id)
                        .and(dsl::file_path.eq(file_path))
                        .and(dsl::status.eq(InsightJobStatus::Running.as_str())),
                ),
            )
            .set((
                dsl::status.eq(InsightJobStatus::Cancelled.as_str()),
                dsl::completed_at.eq(Some(now)),
                dsl::error_message.eq(Some("cancelled by newer request".to_string())),
            ))
            .execute(connection.deref_mut())
            .map_err(|e| anyhow::anyhow!("Failed to cancel active jobs: {}", e))?;

            Ok(rows)
        })
        .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
    }

    fn get_active_job(
        &mut self,
        context: &opentelemetry::Context,
        library_id: i32,
        file_path: &str,
    ) -> Result<Option<InsightGenerationJob>, DbError> {
        trace_db_call(context, "query", "get_active_job", |_span| {
            use schema::insight_generation_jobs::dsl;

            let mut connection = self
                .connection
                .lock()
                .expect("Unable to lock InsightGenerationJobDao");

            dsl::insight_generation_jobs
                .filter(
                    dsl::library_id
                        .eq(library_id)
                        .and(dsl::file_path.eq(file_path))
                        .and(dsl::status.eq(InsightJobStatus::Running.as_str())),
                )
                .order(dsl::id.desc())
                .first::<InsightGenerationJob>(connection.deref_mut())
                .optional()
                .map_err(|e| anyhow::anyhow!("Failed to get active job: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn get_job_by_id(
        &mut self,
        context: &opentelemetry::Context,
        job_id: i32,
    ) -> Result<Option<InsightGenerationJob>, DbError> {
        trace_db_call(context, "query", "get_job_by_id", |_span| {
            use schema::insight_generation_jobs::dsl;

            let mut connection = self
                .connection
                .lock()
                .expect("Unable to lock InsightGenerationJobDao");

            dsl::insight_generation_jobs
                .filter(dsl::id.eq(job_id))
                .first::<InsightGenerationJob>(connection.deref_mut())
                .optional()
                .map_err(|e| anyhow::anyhow!("Failed to get job: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn recover_orphaned_jobs(
        &mut self,
        context: &opentelemetry::Context,
    ) -> Result<usize, DbError> {
        trace_db_call(context, "update", "recover_orphaned_jobs", |_span| {
            use schema::insight_generation_jobs::dsl;

            let mut connection = self
                .connection
                .lock()
                .expect("Unable to lock InsightGenerationJobDao");

            let now = std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("Time went backwards")
                .as_secs() as i64;

            let rows = diesel::update(
                dsl::insight_generation_jobs
                    .filter(dsl::status.eq(InsightJobStatus::Running.as_str())),
            )
            .set((
                dsl::status.eq(InsightJobStatus::Failed.as_str()),
                dsl::completed_at.eq(Some(now)),
                dsl::error_message.eq(Some("server crashed while running".to_string())),
            ))
            .execute(connection.deref_mut())
            .map_err(|e| anyhow::anyhow!("Failed to recover orphaned jobs: {}", e))?;

            Ok(rows)
        })
        .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use diesel::Connection;
    use diesel_migrations::{EmbeddedMigrations, MigrationHarness, embed_migrations};

    const DB_MIGRATIONS: EmbeddedMigrations = embed_migrations!();

    fn setup_dao() -> SqliteInsightGenerationJobDao {
        let mut conn = SqliteConnection::establish(":memory:")
            .expect("Unable to create in-memory db connection");
        conn.run_pending_migrations(DB_MIGRATIONS)
            .expect("Failure running DB migrations");
        SqliteInsightGenerationJobDao::from_connection(Arc::new(Mutex::new(conn)))
    }

    fn ctx() -> opentelemetry::Context {
        opentelemetry::Context::new()
    }

    #[test]
    fn create_job_inserts_new_row() {
        let mut dao = setup_dao();
        let ctx = ctx();

        let job_id_1 = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Standard)
            .unwrap();

        let job_id_2 = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Standard)
            .unwrap();

        assert_ne!(job_id_1, job_id_2, "each create_job call inserts a new row");
    }

    #[test]
    fn complete_job_sets_result() {
        let mut dao = setup_dao();
        let ctx = ctx();

        let job_id = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Standard)
            .unwrap();

        dao.complete_job(&ctx, job_id, 42).unwrap();

        let job = dao.get_job_by_id(&ctx, job_id).unwrap().unwrap();
        assert_eq!(job.status, InsightJobStatus::Completed.as_str());
        assert_eq!(job.result_insight_id, Some(42));
        assert!(job.completed_at.is_some());
    }

    #[test]
    fn fail_job_sets_error() {
        let mut dao = setup_dao();
        let ctx = ctx();

        let job_id = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Agentic)
            .unwrap();

        dao.fail_job(&ctx, job_id, "model timeout").unwrap();

        let job = dao.get_job_by_id(&ctx, job_id).unwrap().unwrap();
        assert_eq!(job.status, InsightJobStatus::Failed.as_str());
        assert_eq!(job.error_message.as_deref(), Some("model timeout"));
        assert!(job.completed_at.is_some());
    }

    #[test]
    fn get_active_job_returns_none_when_completed() {
        let mut dao = setup_dao();
        let ctx = ctx();

        let job_id = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Standard)
            .unwrap();

        // Job is running
        let active = dao.get_active_job(&ctx, 1, "photos/test.jpg").unwrap();
        assert!(active.is_some());
        assert_eq!(active.unwrap().id, job_id);

        // Complete it
        dao.complete_job(&ctx, job_id, 1).unwrap();

        // No longer active
        let active = dao.get_active_job(&ctx, 1, "photos/test.jpg").unwrap();
        assert!(active.is_none());
    }

    #[test]
    fn cancel_active_jobs() {
        let mut dao = setup_dao();
        let ctx = ctx();

        let job_id = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Standard)
            .unwrap();

        let cancelled = dao.cancel_active_jobs(&ctx, 1, "photos/test.jpg").unwrap();
        assert_eq!(cancelled, 1, "should cancel 1 running job");

        // Job is no longer active
        let active = dao.get_active_job(&ctx, 1, "photos/test.jpg").unwrap();
        assert!(active.is_none());

        // Job exists with cancelled status
        let job = dao.get_job_by_id(&ctx, job_id).unwrap().unwrap();
        assert_eq!(job.status, InsightJobStatus::Cancelled.as_str());

        // Cancelling again returns 0 (nothing to cancel)
        let cancelled2 = dao.cancel_active_jobs(&ctx, 1, "photos/test.jpg").unwrap();
        assert_eq!(cancelled2, 0, "should return 0 when no running job");
    }

    #[test]
    fn get_active_job_scoped_by_library() {
        let mut dao = setup_dao();
        let ctx = ctx();

        let job_id_1 = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Standard)
            .unwrap();

        let job_id_2 = dao
            .create_job(&ctx, 2, "photos/test.jpg", InsightGenerationType::Standard)
            .unwrap();

        assert_ne!(
            job_id_1, job_id_2,
            "different libraries should have separate jobs"
        );

        // Complete lib1's job
        dao.complete_job(&ctx, job_id_1, 1).unwrap();

        // lib1 has no active job
        let active1 = dao.get_active_job(&ctx, 1, "photos/test.jpg").unwrap();
        assert!(active1.is_none());

        // lib2 still has active job
        let active2 = dao.get_active_job(&ctx, 2, "photos/test.jpg").unwrap();
        assert!(active2.is_some());
        assert_eq!(active2.unwrap().id, job_id_2);
    }

    #[test]
    fn get_job_by_id_finds_any_status() {
        let mut dao = setup_dao();
        let ctx = ctx();

        let job_id = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Standard)
            .unwrap();

        // Find while running
        let job = dao.get_job_by_id(&ctx, job_id).unwrap().unwrap();
        assert_eq!(job.status, InsightJobStatus::Running.as_str());

        // Complete it
        dao.complete_job(&ctx, job_id, 99).unwrap();

        // Still findable
        let job = dao.get_job_by_id(&ctx, job_id).unwrap().unwrap();
        assert_eq!(job.status, InsightJobStatus::Completed.as_str());
        assert_eq!(job.result_insight_id, Some(99));
    }

    #[test]
    fn recover_orphaned_jobs() {
        let mut dao = setup_dao();
        let ctx = ctx();

        // Create two running jobs
        let job_id_1 = dao
            .create_job(&ctx, 1, "photos/a.jpg", InsightGenerationType::Standard)
            .unwrap();
        let job_id_2 = dao
            .create_job(&ctx, 1, "photos/b.jpg", InsightGenerationType::Agentic)
            .unwrap();

        // Complete one
        dao.complete_job(&ctx, job_id_1, 1).unwrap();

        // Recover should only affect the running job
        let recovered = dao.recover_orphaned_jobs(&ctx).unwrap();
        assert_eq!(recovered, 1, "should recover exactly 1 running job");

        // job_id_1 is still completed
        let job1 = dao.get_job_by_id(&ctx, job_id_1).unwrap().unwrap();
        assert_eq!(job1.status, InsightJobStatus::Completed.as_str());

        // job_id_2 is now failed with recovery message
        let job2 = dao.get_job_by_id(&ctx, job_id_2).unwrap().unwrap();
        assert_eq!(job2.status, InsightJobStatus::Failed.as_str());
        assert_eq!(
            job2.error_message.as_deref(),
            Some("server crashed while running")
        );

        // Second recovery is a no-op
        let recovered2 = dao.recover_orphaned_jobs(&ctx).unwrap();
        assert_eq!(recovered2, 0, "no running jobs remain");
    }

    #[test]
    fn complete_job_noop_when_cancelled() {
        let mut dao = setup_dao();
        let ctx = ctx();

        let job_id = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Standard)
            .unwrap();

        dao.cancel_job(&ctx, job_id).unwrap();

        // Late-completing task tries to mark as completed — should be a no-op
        dao.complete_job(&ctx, job_id, 42).unwrap();

        let job = dao.get_job_by_id(&ctx, job_id).unwrap().unwrap();
        assert_eq!(
            job.status,
            InsightJobStatus::Cancelled.as_str(),
            "cancelled status must not be overwritten by late complete"
        );
        assert_eq!(
            job.result_insight_id, None,
            "insight_id must stay None when complete is a no-op"
        );
    }

    #[test]
    fn fail_job_noop_when_cancelled() {
        let mut dao = setup_dao();
        let ctx = ctx();

        let job_id = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Agentic)
            .unwrap();

        dao.cancel_job(&ctx, job_id).unwrap();

        // Late-failing task tries to mark as failed — should be a no-op
        dao.fail_job(&ctx, job_id, "timeout after 120s").unwrap();

        let job = dao.get_job_by_id(&ctx, job_id).unwrap().unwrap();
        assert_eq!(
            job.status,
            InsightJobStatus::Cancelled.as_str(),
            "cancelled status must not be overwritten by late fail"
        );
        assert_eq!(
            job.error_message.as_deref(),
            Some("cancelled by user"),
            "error_message must reflect the cancel, not the late fail"
        );
    }

    #[test]
    fn cancel_job_by_id() {
        let mut dao = setup_dao();
        let ctx = ctx();

        let job_id = dao
            .create_job(&ctx, 1, "photos/test.jpg", InsightGenerationType::Standard)
            .unwrap();

        let cancelled = dao.cancel_job(&ctx, job_id).unwrap();
        assert!(cancelled, "should cancel running job");

        let job = dao.get_job_by_id(&ctx, job_id).unwrap().unwrap();
        assert_eq!(job.status, InsightJobStatus::Cancelled.as_str());
        assert!(job.completed_at.is_some());

        // Cancelling again is a no-op
        let cancelled2 = dao.cancel_job(&ctx, job_id).unwrap();
        assert!(!cancelled2, "already cancelled job should return false");
    }
}