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

use crate::database::models::{InsertPhotoInsight, PhotoInsight};
use crate::database::schema;
use crate::database::{DbError, DbErrorKind, connect};
use crate::otel::trace_db_call;

pub trait InsightDao: Sync + Send {
    fn store_insight(
        &mut self,
        context: &opentelemetry::Context,
        insight: InsertPhotoInsight,
    ) -> Result<PhotoInsight, DbError>;

    fn get_insight(
        &mut self,
        context: &opentelemetry::Context,
        file_path: &str,
    ) -> Result<Option<PhotoInsight>, DbError>;

    /// Library-scoped variant of `get_insight`. The default `get_insight`
    /// finds any `is_current=true` row matching `file_path` across
    /// libraries — fine for the photo-grid metadata fetch (cross-library
    /// merge), wrong for the chat path: a regenerate on lib1 flips lib1's
    /// row to `is_current=false` and inserts a new lib1 row, but
    /// lib2's untouched `is_current=true` row for the same rel_path
    /// would still satisfy the path-only query and shadow the regen on
    /// the next history fetch. Always pass a library_id when you have
    /// one (chat / insight write paths always do).
    fn get_current_insight_for_library(
        &mut self,
        context: &opentelemetry::Context,
        library_id: i32,
        file_path: &str,
    ) -> Result<Option<PhotoInsight>, DbError>;

    /// Return the most recent current insight whose rel_path is one of
    /// `paths`. Used for content-hash sharing: the caller expands a
    /// single file into all rel_paths with the same content_hash, then
    /// asks here for any existing insight attached to any of them.
    fn get_insight_for_paths(
        &mut self,
        context: &opentelemetry::Context,
        paths: &[String],
    ) -> Result<Option<PhotoInsight>, DbError>;

    fn get_insight_history(
        &mut self,
        context: &opentelemetry::Context,
        file_path: &str,
    ) -> Result<Vec<PhotoInsight>, DbError>;

    /// Fetch a single insight by primary key, regardless of `is_current`.
    /// Used by the few-shot injection flow where the caller picks specific
    /// historical insights (which may have been superseded) as training
    /// exemplars for a fresh generation.
    fn get_insight_by_id(
        &mut self,
        context: &opentelemetry::Context,
        insight_id: i32,
    ) -> Result<Option<PhotoInsight>, DbError>;

    fn delete_insight(
        &mut self,
        context: &opentelemetry::Context,
        file_path: &str,
    ) -> Result<(), DbError>;

    fn get_all_insights(
        &mut self,
        context: &opentelemetry::Context,
    ) -> Result<Vec<PhotoInsight>, DbError>;

    fn rate_insight(
        &mut self,
        context: &opentelemetry::Context,
        file_path: &str,
        approved: bool,
    ) -> Result<(), DbError>;

    /// Rate a specific insight version by primary key, regardless of
    /// `is_current`. Used by the per-file history view to approve/reject
    /// previously generated (superseded) versions, which the path-based
    /// `rate_insight` (current row only) cannot reach.
    fn rate_insight_by_id(
        &mut self,
        context: &opentelemetry::Context,
        insight_id: i32,
        approved: bool,
    ) -> Result<(), DbError>;

    fn get_approved_insights(
        &mut self,
        context: &opentelemetry::Context,
    ) -> Result<Vec<PhotoInsight>, DbError>;

    /// Replace the `training_messages` JSON blob on the current row for
    /// `(library_id, rel_path)`. Used by chat-turn append mode to persist
    /// the extended conversation without inserting a new insight version.
    /// Returns the number of rows affected (0 if no current row matched,
    /// indicating a concurrent regenerate/reconcile flipped `is_current`).
    fn update_training_messages(
        &mut self,
        context: &opentelemetry::Context,
        library_id: i32,
        file_path: &str,
        training_messages_json: &str,
    ) -> Result<usize, DbError>;
}

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

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

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

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

impl InsightDao for SqliteInsightDao {
    fn store_insight(
        &mut self,
        context: &opentelemetry::Context,
        mut insight: InsertPhotoInsight,
    ) -> Result<PhotoInsight, DbError> {
        trace_db_call(context, "insert", "store_insight", |_span| {
            use schema::photo_insights::dsl::*;

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

            // Eagerly populate content_hash so this insight follows the
            // bytes (CLAUDE.md "Multi-library data model"). Caller-
            // supplied hash wins; otherwise look it up from image_exif
            // for the (library_id, rel_path) tuple. None is acceptable —
            // reconciliation backfills it once the hash lands.
            if insight.content_hash.is_none() {
                use schema::image_exif as ie;
                insight.content_hash = ie::table
                    .filter(ie::library_id.eq(insight.library_id))
                    .filter(ie::rel_path.eq(&insight.file_path))
                    .filter(ie::content_hash.is_not_null())
                    .select(ie::content_hash)
                    .first::<Option<String>>(connection.deref_mut())
                    .ok()
                    .flatten();
            }

            // Mark all existing insights for this file as no longer current
            diesel::update(
                photo_insights
                    .filter(library_id.eq(insight.library_id))
                    .filter(rel_path.eq(&insight.file_path)),
            )
            .set(is_current.eq(false))
            .execute(connection.deref_mut())
            .map_err(|e| anyhow::anyhow!("Failed to flip is_current: {}", e))?;

            // Insert the new insight as current
            diesel::insert_into(photo_insights)
                .values(&insight)
                .execute(connection.deref_mut())
                .map_err(|e| anyhow::anyhow!("Failed to insert insight: {}", e))?;

            // Retrieve the inserted record (is_current = true)
            photo_insights
                .filter(library_id.eq(insight.library_id))
                .filter(rel_path.eq(&insight.file_path))
                .filter(is_current.eq(true))
                .first::<PhotoInsight>(connection.deref_mut())
                .map_err(|e| anyhow::anyhow!("Failed to retrieve inserted insight: {}", e))
        })
        .map_err(|e| {
            log::error!("store_insight failed: {}", e);
            DbError::new(DbErrorKind::InsertError)
        })
    }

    fn get_insight(
        &mut self,
        context: &opentelemetry::Context,
        path: &str,
    ) -> Result<Option<PhotoInsight>, DbError> {
        trace_db_call(context, "query", "get_insight", |_span| {
            use schema::photo_insights::dsl::*;

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

            photo_insights
                .filter(rel_path.eq(path))
                .filter(is_current.eq(true))
                .first::<PhotoInsight>(connection.deref_mut())
                .optional()
                .map_err(|e| anyhow::anyhow!("Query error: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn get_current_insight_for_library(
        &mut self,
        context: &opentelemetry::Context,
        lib_id: i32,
        path: &str,
    ) -> Result<Option<PhotoInsight>, DbError> {
        trace_db_call(
            context,
            "query",
            "get_current_insight_for_library",
            |_span| {
                use schema::photo_insights::dsl::*;

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

                photo_insights
                    .filter(library_id.eq(lib_id))
                    .filter(rel_path.eq(path))
                    .filter(is_current.eq(true))
                    .first::<PhotoInsight>(connection.deref_mut())
                    .optional()
                    .map_err(|e| anyhow::anyhow!("Query error: {}", e))
            },
        )
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn get_insight_for_paths(
        &mut self,
        context: &opentelemetry::Context,
        paths: &[String],
    ) -> Result<Option<PhotoInsight>, DbError> {
        if paths.is_empty() {
            return Ok(None);
        }
        trace_db_call(context, "query", "get_insight_for_paths", |_span| {
            use schema::photo_insights::dsl::*;

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

            photo_insights
                .filter(rel_path.eq_any(paths))
                .filter(is_current.eq(true))
                .order(generated_at.desc())
                .first::<PhotoInsight>(connection.deref_mut())
                .optional()
                .map_err(|e| anyhow::anyhow!("Query error: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn get_insight_history(
        &mut self,
        context: &opentelemetry::Context,
        path: &str,
    ) -> Result<Vec<PhotoInsight>, DbError> {
        trace_db_call(context, "query", "get_insight_history", |_span| {
            use schema::photo_insights::dsl::*;

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

            photo_insights
                .filter(rel_path.eq(path))
                .order(generated_at.desc())
                .load::<PhotoInsight>(connection.deref_mut())
                .map_err(|e| anyhow::anyhow!("Query error: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn get_insight_by_id(
        &mut self,
        context: &opentelemetry::Context,
        insight_id: i32,
    ) -> Result<Option<PhotoInsight>, DbError> {
        trace_db_call(context, "query", "get_insight_by_id", |_span| {
            use schema::photo_insights::dsl::*;

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

            photo_insights
                .find(insight_id)
                .first::<PhotoInsight>(connection.deref_mut())
                .optional()
                .map_err(|e| anyhow::anyhow!("Query error: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn delete_insight(
        &mut self,
        context: &opentelemetry::Context,
        path: &str,
    ) -> Result<(), DbError> {
        trace_db_call(context, "delete", "delete_insight", |_span| {
            use schema::photo_insights::dsl::*;

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

            diesel::delete(photo_insights.filter(rel_path.eq(path)))
                .execute(connection.deref_mut())
                .map(|_| ())
                .map_err(|e| anyhow::anyhow!("Delete error: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn get_all_insights(
        &mut self,
        context: &opentelemetry::Context,
    ) -> Result<Vec<PhotoInsight>, DbError> {
        trace_db_call(context, "query", "get_all_insights", |_span| {
            use schema::photo_insights::dsl::*;

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

            photo_insights
                .filter(is_current.eq(true))
                .order(generated_at.desc())
                .load::<PhotoInsight>(connection.deref_mut())
                .map_err(|e| anyhow::anyhow!("Query error: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn rate_insight(
        &mut self,
        context: &opentelemetry::Context,
        path: &str,
        is_approved: bool,
    ) -> Result<(), DbError> {
        trace_db_call(context, "update", "rate_insight", |_span| {
            use schema::photo_insights::dsl::*;

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

            diesel::update(
                photo_insights
                    .filter(rel_path.eq(path))
                    .filter(is_current.eq(true)),
            )
            .set(approved.eq(Some(is_approved)))
            .execute(connection.deref_mut())
            .map(|_| ())
            .map_err(|e| anyhow::anyhow!("Update error: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
    }

    fn rate_insight_by_id(
        &mut self,
        context: &opentelemetry::Context,
        target_id: i32,
        is_approved: bool,
    ) -> Result<(), DbError> {
        trace_db_call(context, "update", "rate_insight_by_id", |_span| {
            use schema::photo_insights::dsl::*;

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

            diesel::update(photo_insights.find(target_id))
                .set(approved.eq(Some(is_approved)))
                .execute(connection.deref_mut())
                .map(|_| ())
                .map_err(|e| anyhow::anyhow!("Update error: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
    }

    fn get_approved_insights(
        &mut self,
        context: &opentelemetry::Context,
    ) -> Result<Vec<PhotoInsight>, DbError> {
        trace_db_call(context, "query", "get_approved_insights", |_span| {
            use schema::photo_insights::dsl::*;

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

            photo_insights
                .filter(approved.eq(true))
                .filter(training_messages.is_not_null())
                .order(generated_at.desc())
                .load::<PhotoInsight>(connection.deref_mut())
                .map_err(|e| anyhow::anyhow!("Query error: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::QueryError, e))
    }

    fn update_training_messages(
        &mut self,
        context: &opentelemetry::Context,
        lib_id: i32,
        path: &str,
        training_messages_json: &str,
    ) -> Result<usize, DbError> {
        trace_db_call(context, "update", "update_training_messages", |_span| {
            use schema::photo_insights::dsl::*;

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

            diesel::update(
                photo_insights
                    .filter(library_id.eq(lib_id))
                    .filter(rel_path.eq(path))
                    .filter(is_current.eq(true)),
            )
            .set(training_messages.eq(Some(training_messages_json.to_string())))
            .execute(connection.deref_mut())
            .map_err(|e| anyhow::anyhow!("Update error: {}", e))
        })
        .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::database::test::in_memory_db_connection;

    fn dao() -> SqliteInsightDao {
        let conn = Arc::new(Mutex::new(in_memory_db_connection()));
        SqliteInsightDao::from_connection(conn)
    }

    /// Build an insight insert with sensible defaults; tests override the
    /// fields they care about (path, generated_at, model).
    fn insert(path: &str, generated_at: i64, model: &str) -> InsertPhotoInsight {
        InsertPhotoInsight {
            library_id: 1,
            file_path: path.to_string(),
            title: format!("title for {model}"),
            summary: "summary".to_string(),
            generated_at,
            model_version: model.to_string(),
            is_current: true,
            training_messages: None,
            backend: "local".to_string(),
            fewshot_source_ids: None,
            content_hash: None,
            num_ctx: None,
            temperature: None,
            top_p: None,
            top_k: None,
            min_p: None,
            system_prompt: None,
            persona_id: None,
            prompt_eval_count: None,
            eval_count: None,
        }
    }

    #[test]
    fn get_insight_history_returns_all_versions_newest_first() {
        let cx = opentelemetry::Context::new();
        let mut dao = dao();

        // store_insight flips prior rows to is_current=false, so three
        // generations for the same path leave a 3-row history.
        dao.store_insight(&cx, insert("a.jpg", 100, "m1")).unwrap();
        dao.store_insight(&cx, insert("a.jpg", 200, "m2")).unwrap();
        dao.store_insight(&cx, insert("a.jpg", 300, "m3")).unwrap();
        // A different path must not leak into the history.
        dao.store_insight(&cx, insert("b.jpg", 250, "other"))
            .unwrap();

        let history = dao.get_insight_history(&cx, "a.jpg").unwrap();
        assert_eq!(history.len(), 3);
        assert_eq!(
            history.iter().map(|i| i.generated_at).collect::<Vec<_>>(),
            vec![300, 200, 100],
            "history should be newest-first"
        );
        // Exactly one version is current (the latest generation).
        let current: Vec<_> = history.iter().filter(|i| i.is_current).collect();
        assert_eq!(current.len(), 1);
        assert_eq!(current[0].generated_at, 300);
    }

    #[test]
    fn rate_insight_by_id_rates_only_the_targeted_version() {
        let cx = opentelemetry::Context::new();
        let mut dao = dao();

        dao.store_insight(&cx, insert("a.jpg", 100, "m1")).unwrap();
        dao.store_insight(&cx, insert("a.jpg", 200, "m2")).unwrap();

        // History is newest-first: [200 (current), 100 (superseded)].
        let history = dao.get_insight_history(&cx, "a.jpg").unwrap();
        let old_version = history.iter().find(|i| i.generated_at == 100).unwrap();
        assert!(!old_version.is_current);

        dao.rate_insight_by_id(&cx, old_version.id, true).unwrap();

        let history = dao.get_insight_history(&cx, "a.jpg").unwrap();
        let old = history.iter().find(|i| i.generated_at == 100).unwrap();
        let current = history.iter().find(|i| i.generated_at == 200).unwrap();
        assert_eq!(old.approved, Some(true), "targeted version is rated");
        assert_eq!(current.approved, None, "current version is untouched");
    }
}