use anyhow::Result;
use db::{
    query,
    sqlez::{
        bindable::{Bind, Column, StaticColumnCount},
        domain::Domain,
        statement::Statement,
    },
    sqlez_macros::sql,
};
use fs::MTime;
use itertools::Itertools as _;
use std::path::PathBuf;

use workspace::{ItemId, WorkspaceDb, WorkspaceId};

#[derive(Clone, Debug, PartialEq, Default)]
pub(crate) struct SerializedEditor {
    pub(crate) abs_path: Option<PathBuf>,
    pub(crate) contents: Option<String>,
    pub(crate) language: Option<String>,
    pub(crate) mtime: Option<MTime>,
}

impl StaticColumnCount for SerializedEditor {
    fn column_count() -> usize {
        6
    }
}

impl Bind for SerializedEditor {
    fn bind(&self, statement: &Statement, start_index: i32) -> Result<i32> {
        let start_index = statement.bind(&self.abs_path, start_index)?;
        let start_index = statement.bind(
            &self
                .abs_path
                .as_ref()
                .map(|p| p.to_string_lossy().into_owned()),
            start_index,
        )?;
        let start_index = statement.bind(&self.contents, start_index)?;
        let start_index = statement.bind(&self.language, start_index)?;

        let start_index = match self
            .mtime
            .and_then(|mtime| mtime.to_seconds_and_nanos_for_persistence())
        {
            Some((seconds, nanos)) => {
                let start_index = statement.bind(&(seconds as i64), start_index)?;
                statement.bind(&(nanos as i32), start_index)?
            }
            None => {
                let start_index = statement.bind::<Option<i64>>(&None, start_index)?;
                statement.bind::<Option<i32>>(&None, start_index)?
            }
        };
        Ok(start_index)
    }
}

impl Column for SerializedEditor {
    fn column(statement: &mut Statement, start_index: i32) -> Result<(Self, i32)> {
        let (abs_path, start_index): (Option<PathBuf>, i32) =
            Column::column(statement, start_index)?;
        let (_abs_path, start_index): (Option<PathBuf>, i32) =
            Column::column(statement, start_index)?;
        let (contents, start_index): (Option<String>, i32) =
            Column::column(statement, start_index)?;
        let (language, start_index): (Option<String>, i32) =
            Column::column(statement, start_index)?;
        let (mtime_seconds, start_index): (Option<i64>, i32) =
            Column::column(statement, start_index)?;
        let (mtime_nanos, start_index): (Option<i32>, i32) =
            Column::column(statement, start_index)?;

        let mtime = mtime_seconds
            .zip(mtime_nanos)
            .map(|(seconds, nanos)| MTime::from_seconds_and_nanos(seconds as u64, nanos as u32));

        let editor = Self {
            abs_path,
            contents,
            language,
            mtime,
        };
        Ok((editor, start_index))
    }
}

pub struct EditorDb(db::sqlez::thread_safe_connection::ThreadSafeConnection);

impl Domain for EditorDb {
    const NAME: &str = stringify!(EditorDb);

    // Current schema shape using pseudo-rust syntax:
    // editors(
    //   item_id: usize,
    //   workspace_id: usize,
    //   path: Option<PathBuf>,
    //   scroll_top_row: usize,
    //   scroll_vertical_offset: f32,
    //   scroll_horizontal_offset: f32,
    //   contents: Option<String>,
    //   language: Option<String>,
    //   mtime_seconds: Option<i64>,
    //   mtime_nanos: Option<i32>,
    // )
    //
    // editor_selections(
    //   item_id: usize,
    //   editor_id: usize,
    //   workspace_id: usize,
    //   start: usize,
    //   end: usize,
    // )
    //
    // editor_folds(
    //   item_id: usize,
    //   editor_id: usize,
    //   workspace_id: usize,
    //   start: usize,
    //   end: usize,
    //   start_fingerprint: Option<String>,
    //   end_fingerprint: Option<String>,
    // )

    const MIGRATIONS: &[&str] = &[
        sql! (
            CREATE TABLE editors(
                item_id INTEGER NOT NULL,
                workspace_id INTEGER NOT NULL,
                path BLOB NOT NULL,
                PRIMARY KEY(item_id, workspace_id),
                FOREIGN KEY(workspace_id) REFERENCES workspaces(workspace_id)
                ON DELETE CASCADE
                ON UPDATE CASCADE
            ) STRICT;
        ),
        sql! (
            ALTER TABLE editors ADD COLUMN scroll_top_row INTEGER NOT NULL DEFAULT 0;
            ALTER TABLE editors ADD COLUMN scroll_horizontal_offset REAL NOT NULL DEFAULT 0;
            ALTER TABLE editors ADD COLUMN scroll_vertical_offset REAL NOT NULL DEFAULT 0;
        ),
        sql! (
            // Since sqlite3 doesn't support ALTER COLUMN, we create a new
            // table, move the data over, drop the old table, rename new table.
            CREATE TABLE new_editors_tmp (
                item_id INTEGER NOT NULL,
                workspace_id INTEGER NOT NULL,
                path BLOB, // <-- No longer "NOT NULL"
                scroll_top_row INTEGER NOT NULL DEFAULT 0,
                scroll_horizontal_offset REAL NOT NULL DEFAULT 0,
                scroll_vertical_offset REAL NOT NULL DEFAULT 0,
                contents TEXT, // New
                language TEXT, // New
                PRIMARY KEY(item_id, workspace_id),
                FOREIGN KEY(workspace_id) REFERENCES workspaces(workspace_id)
                ON DELETE CASCADE
                ON UPDATE CASCADE
            ) STRICT;

            INSERT INTO new_editors_tmp(item_id, workspace_id, path, scroll_top_row, scroll_horizontal_offset, scroll_vertical_offset)
            SELECT item_id, workspace_id, path, scroll_top_row, scroll_horizontal_offset, scroll_vertical_offset
            FROM editors;

            DROP TABLE editors;

            ALTER TABLE new_editors_tmp RENAME TO editors;
        ),
        sql! (
            ALTER TABLE editors ADD COLUMN mtime_seconds INTEGER DEFAULT NULL;
            ALTER TABLE editors ADD COLUMN mtime_nanos INTEGER DEFAULT NULL;
        ),
        sql! (
            CREATE TABLE editor_selections (
                item_id INTEGER NOT NULL,
                editor_id INTEGER NOT NULL,
                workspace_id INTEGER NOT NULL,
                start INTEGER NOT NULL,
                end INTEGER NOT NULL,
                PRIMARY KEY(item_id),
                FOREIGN KEY(editor_id, workspace_id) REFERENCES editors(item_id, workspace_id)
                ON DELETE CASCADE
            ) STRICT;
        ),
        sql! (
            ALTER TABLE editors ADD COLUMN buffer_path TEXT;
            UPDATE editors SET buffer_path = CAST(path AS TEXT);
        ),
        sql! (
            CREATE TABLE editor_folds (
                item_id INTEGER NOT NULL,
                editor_id INTEGER NOT NULL,
                workspace_id INTEGER NOT NULL,
                start INTEGER NOT NULL,
                end INTEGER NOT NULL,
                PRIMARY KEY(item_id),
                FOREIGN KEY(editor_id, workspace_id) REFERENCES editors(item_id, workspace_id)
                ON DELETE CASCADE
            ) STRICT;
        ),
        sql! (
            ALTER TABLE editor_folds ADD COLUMN start_fingerprint TEXT;
            ALTER TABLE editor_folds ADD COLUMN end_fingerprint TEXT;
        ),
    ];
}

db::static_connection!(DB, EditorDb, [WorkspaceDb]);

// https://www.sqlite.org/limits.html
// > <..> the maximum value of a host parameter number is SQLITE_MAX_VARIABLE_NUMBER,
// > which defaults to <..> 32766 for SQLite versions after 3.32.0.
const MAX_QUERY_PLACEHOLDERS: usize = 32000;

impl EditorDb {
    query! {
        pub fn get_serialized_editor(item_id: ItemId, workspace_id: WorkspaceId) -> Result<Option<SerializedEditor>> {
            SELECT path, buffer_path, contents, language, mtime_seconds, mtime_nanos FROM editors
            WHERE item_id = ? AND workspace_id = ?
        }
    }

    query! {
        pub async fn save_serialized_editor(item_id: ItemId, workspace_id: WorkspaceId, serialized_editor: SerializedEditor) -> Result<()> {
            INSERT INTO editors
                (item_id, workspace_id, path, buffer_path, contents, language, mtime_seconds, mtime_nanos)
            VALUES
                (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)
            ON CONFLICT DO UPDATE SET
                item_id = ?1,
                workspace_id = ?2,
                path = ?3,
                buffer_path = ?4,
                contents = ?5,
                language = ?6,
                mtime_seconds = ?7,
                mtime_nanos = ?8
        }
    }

    // Returns the scroll top row, and offset
    query! {
        pub fn get_scroll_position(item_id: ItemId, workspace_id: WorkspaceId) -> Result<Option<(u32, f64, f64)>> {
            SELECT scroll_top_row, scroll_horizontal_offset, scroll_vertical_offset
            FROM editors
            WHERE item_id = ? AND workspace_id = ?
        }
    }

    query! {
        pub async fn save_scroll_position(
            item_id: ItemId,
            workspace_id: WorkspaceId,
            top_row: u32,
            vertical_offset: f64,
            horizontal_offset: f64
        ) -> Result<()> {
            UPDATE OR IGNORE editors
            SET
                scroll_top_row = ?3,
                scroll_horizontal_offset = ?4,
                scroll_vertical_offset = ?5
            WHERE item_id = ?1 AND workspace_id = ?2
        }
    }

    query! {
        pub fn get_editor_selections(
            editor_id: ItemId,
            workspace_id: WorkspaceId
        ) -> Result<Vec<(usize, usize)>> {
            SELECT start, end
            FROM editor_selections
            WHERE editor_id = ?1 AND workspace_id = ?2
        }
    }

    query! {
        pub fn get_editor_folds(
            editor_id: ItemId,
            workspace_id: WorkspaceId
        ) -> Result<Vec<(usize, usize, Option<String>, Option<String>)>> {
            SELECT start, end, start_fingerprint, end_fingerprint
            FROM editor_folds
            WHERE editor_id = ?1 AND workspace_id = ?2
        }
    }

    // Migrate folds from an old editor_id to a new one.
    // This is needed because entity IDs change between sessions, but workspace
    // cleanup deletes old editor rows (cascading to folds) before the new
    // editor has a chance to re-save its folds.
    //
    // We temporarily disable FK checks because the new editor row doesn't exist
    // yet (it gets created during workspace serialization, which runs later).
    pub async fn migrate_editor_folds(
        &self,
        old_editor_id: ItemId,
        new_editor_id: ItemId,
        workspace_id: WorkspaceId,
    ) -> Result<()> {
        self.write(move |conn| {
            let _ = conn.exec("PRAGMA foreign_keys = OFF");
            let mut statement = Statement::prepare(
                conn,
                "UPDATE editor_folds SET editor_id = ?2 WHERE editor_id = ?1 AND workspace_id = ?3",
            )?;
            statement.bind(&old_editor_id, 1)?;
            statement.bind(&new_editor_id, 2)?;
            statement.bind(&workspace_id, 3)?;
            let result = statement.exec();
            let _ = conn.exec("PRAGMA foreign_keys = ON");
            result
        })
        .await
    }

    pub async fn save_editor_selections(
        &self,
        editor_id: ItemId,
        workspace_id: WorkspaceId,
        selections: Vec<(usize, usize)>,
    ) -> Result<()> {
        log::debug!("Saving selections for editor {editor_id} in workspace {workspace_id:?}");
        let mut first_selection;
        let mut last_selection = 0_usize;
        for (count, placeholders) in std::iter::once("(?1, ?2, ?, ?)")
            .cycle()
            .take(selections.len())
            .chunks(MAX_QUERY_PLACEHOLDERS / 4)
            .into_iter()
            .map(|chunk| {
                let mut count = 0;
                let placeholders = chunk
                    .inspect(|_| {
                        count += 1;
                    })
                    .join(", ");
                (count, placeholders)
            })
            .collect::<Vec<_>>()
        {
            first_selection = last_selection;
            last_selection = last_selection + count;
            let query = format!(
                r#"
DELETE FROM editor_selections WHERE editor_id = ?1 AND workspace_id = ?2;

INSERT OR IGNORE INTO editor_selections (editor_id, workspace_id, start, end)
VALUES {placeholders};
"#
            );

            let selections = selections[first_selection..last_selection].to_vec();
            self.write(move |conn| {
                let mut statement = Statement::prepare(conn, query)?;
                statement.bind(&editor_id, 1)?;
                let mut next_index = statement.bind(&workspace_id, 2)?;
                for (start, end) in selections {
                    next_index = statement.bind(&start, next_index)?;
                    next_index = statement.bind(&end, next_index)?;
                }
                statement.exec()
            })
            .await?;
        }
        Ok(())
    }

    pub async fn save_editor_folds(
        &self,
        editor_id: ItemId,
        workspace_id: WorkspaceId,
        folds: Vec<(usize, usize, String, String)>,
    ) -> Result<()> {
        log::debug!("Saving folds for editor {editor_id} in workspace {workspace_id:?}");
        let mut first_fold;
        let mut last_fold = 0_usize;
        for (count, placeholders) in std::iter::once("(?1, ?2, ?, ?, ?, ?)")
            .cycle()
            .take(folds.len())
            .chunks(MAX_QUERY_PLACEHOLDERS / 6)
            .into_iter()
            .map(|chunk| {
                let mut count = 0;
                let placeholders = chunk
                    .inspect(|_| {
                        count += 1;
                    })
                    .join(", ");
                (count, placeholders)
            })
            .collect::<Vec<_>>()
        {
            first_fold = last_fold;
            last_fold = last_fold + count;
            let query = format!(
                r#"
DELETE FROM editor_folds WHERE editor_id = ?1 AND workspace_id = ?2;

INSERT OR IGNORE INTO editor_folds (editor_id, workspace_id, start, end, start_fingerprint, end_fingerprint)
VALUES {placeholders};
"#
            );

            let folds = folds[first_fold..last_fold].to_vec();
            self.write(move |conn| {
                let mut statement = Statement::prepare(conn, query)?;
                statement.bind(&editor_id, 1)?;
                let mut next_index = statement.bind(&workspace_id, 2)?;
                for (start, end, start_fp, end_fp) in folds {
                    next_index = statement.bind(&start, next_index)?;
                    next_index = statement.bind(&end, next_index)?;
                    next_index = statement.bind(&start_fp, next_index)?;
                    next_index = statement.bind(&end_fp, next_index)?;
                }
                statement.exec()
            })
            .await?;
        }
        Ok(())
    }
}

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

    #[gpui::test]
    async fn test_save_and_get_serialized_editor() {
        let workspace_id = workspace::WORKSPACE_DB.next_id().await.unwrap();

        let serialized_editor = SerializedEditor {
            abs_path: Some(PathBuf::from("testing.txt")),
            contents: None,
            language: None,
            mtime: None,
        };

        DB.save_serialized_editor(1234, workspace_id, serialized_editor.clone())
            .await
            .unwrap();

        let have = DB
            .get_serialized_editor(1234, workspace_id)
            .unwrap()
            .unwrap();
        assert_eq!(have, serialized_editor);

        // Now update contents and language
        let serialized_editor = SerializedEditor {
            abs_path: Some(PathBuf::from("testing.txt")),
            contents: Some("Test".to_owned()),
            language: Some("Go".to_owned()),
            mtime: None,
        };

        DB.save_serialized_editor(1234, workspace_id, serialized_editor.clone())
            .await
            .unwrap();

        let have = DB
            .get_serialized_editor(1234, workspace_id)
            .unwrap()
            .unwrap();
        assert_eq!(have, serialized_editor);

        // Now set all the fields to NULL
        let serialized_editor = SerializedEditor {
            abs_path: None,
            contents: None,
            language: None,
            mtime: None,
        };

        DB.save_serialized_editor(1234, workspace_id, serialized_editor.clone())
            .await
            .unwrap();

        let have = DB
            .get_serialized_editor(1234, workspace_id)
            .unwrap()
            .unwrap();
        assert_eq!(have, serialized_editor);

        // Storing and retrieving mtime
        let serialized_editor = SerializedEditor {
            abs_path: None,
            contents: None,
            language: None,
            mtime: Some(MTime::from_seconds_and_nanos(100, 42)),
        };

        DB.save_serialized_editor(1234, workspace_id, serialized_editor.clone())
            .await
            .unwrap();

        let have = DB
            .get_serialized_editor(1234, workspace_id)
            .unwrap()
            .unwrap();
        assert_eq!(have, serialized_editor);
    }

    #[gpui::test]
    async fn test_save_and_get_editor_folds_with_fingerprints() {
        let workspace_id = workspace::WORKSPACE_DB.next_id().await.unwrap();

        // First create an editor entry (folds have FK to editors)
        let serialized_editor = SerializedEditor {
            abs_path: Some(PathBuf::from("test_folds.txt")),
            contents: None,
            language: None,
            mtime: None,
        };
        DB.save_serialized_editor(5678, workspace_id, serialized_editor)
            .await
            .unwrap();

        // Save folds with fingerprints (32-byte content samples at fold boundaries)
        let folds = vec![
            (
                100,
                200,
                "fn main() {".to_string(),
                "} // end main".to_string(),
            ),
            (
                300,
                400,
                "struct Foo {".to_string(),
                "} // end Foo".to_string(),
            ),
        ];
        DB.save_editor_folds(5678, workspace_id, folds.clone())
            .await
            .unwrap();

        // Retrieve and verify fingerprints are preserved
        let retrieved = DB.get_editor_folds(5678, workspace_id).unwrap();
        assert_eq!(retrieved.len(), 2);
        assert_eq!(
            retrieved[0],
            (
                100,
                200,
                Some("fn main() {".to_string()),
                Some("} // end main".to_string())
            )
        );
        assert_eq!(
            retrieved[1],
            (
                300,
                400,
                Some("struct Foo {".to_string()),
                Some("} // end Foo".to_string())
            )
        );

        // Test overwrite: saving new folds replaces old ones
        let new_folds = vec![(
            500,
            600,
            "impl Bar {".to_string(),
            "} // end impl".to_string(),
        )];
        DB.save_editor_folds(5678, workspace_id, new_folds)
            .await
            .unwrap();

        let retrieved = DB.get_editor_folds(5678, workspace_id).unwrap();
        assert_eq!(retrieved.len(), 1);
        assert_eq!(
            retrieved[0],
            (
                500,
                600,
                Some("impl Bar {".to_string()),
                Some("} // end impl".to_string())
            )
        );
    }

    // NOTE: The fingerprint search logic (finding content at new offsets when file
    // is modified externally) is in editor.rs:restore_from_db and requires a full
    // Editor context to test. Manual testing procedure:
    // 1. Open a file, fold some sections, close Zed
    // 2. Add text at the START of the file externally (shifts all offsets)
    // 3. Reopen Zed - folds should be restored at their NEW correct positions
    // The search uses contains_str_at() to find fingerprints in the buffer.
}