minni 0.1.0

use crate::db::Database;
use anyhow::{Context, Result};
use chrono::Utc;
use rusqlite::{params, OptionalExtension};
use serde::{Deserialize, Serialize};
use uuid::Uuid;

/// Task record.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Task {
    pub id: String,
    pub context_id: String,
    pub seq: i64,
    pub title: String,
    pub description: Option<String>,
    pub status: String,
    pub priority: String,
    pub created_at: String,
    pub updated_at: String,
}

/// Task todo item.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TaskTodo {
    pub id: String,
    pub task_id: String,
    pub seq: i64,
    pub text: String,
    pub done: bool,
    pub created_at: String,
}

/// Task with todos.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FullTask {
    pub task: Task,
    pub todos: Vec<TaskTodo>,
}

/// Task storage and lookup.
pub struct TaskManager<'a> {
    db: &'a Database,
}

impl<'a> TaskManager<'a> {
    pub fn new(db: &'a Database) -> Self {
        Self { db }
    }

    /// Ensure a context with the given name exists (creates it if absent) and return its id.
    pub fn ensure_context(&self, name: &str) -> Result<String> {
        let project_path = self.db.project_root.to_string_lossy().to_string();
        let now = Utc::now().to_rfc3339();
        let new_id = Uuid::new_v4().to_string();

        // INSERT OR IGNORE so we don't overwrite an existing context
        self.db
            .conn()
            .execute(
                "INSERT OR IGNORE INTO contexts (id, name, description, created_at, updated_at, project_path)
                 VALUES (?1, ?2, NULL, ?3, ?4, ?5)",
                params![new_id, name, now, now, project_path],
            )
            .with_context(|| format!("Failed to ensure context '{name}'"))?;

        let id: String = self
            .db
            .conn()
            .query_row(
                "SELECT id FROM contexts WHERE name = ?1",
                params![name],
                |row| row.get(0),
            )
            .with_context(|| format!("Failed to fetch context id for '{name}'"))?;

        Ok(id)
    }

    /// Look up a context by name; error if it doesn't exist.
    fn lookup_context_id(&self, context_name: &str) -> Result<String> {
        self.db
            .conn()
            .query_row(
                "SELECT id FROM contexts WHERE name = ?1",
                params![context_name],
                |row| row.get(0),
            )
            .optional()
            .with_context(|| format!("Failed to query context '{context_name}'"))?
            .ok_or_else(|| anyhow::anyhow!("context '{}' not found", context_name))
    }

    /// Add a new task to the named context.
    pub fn add_task(
        &self,
        context_name: &str,
        title: &str,
        description: Option<&str>,
        priority: &str,
    ) -> Result<Task> {
        let context_id = self.ensure_context(context_name)?;
        let now = Utc::now().to_rfc3339();
        let id = Uuid::new_v4().to_string();

        // Determine next seq within this context
        let seq: i64 = self
            .db
            .conn()
            .query_row(
                "SELECT COALESCE(MAX(seq), 0) + 1 FROM tasks WHERE context_id = ?1",
                params![context_id],
                |row| row.get(0),
            )
            .with_context(|| {
                format!("Failed to determine next seq for context '{context_name}'")
            })?;

        self.db
            .conn()
            .execute(
                "INSERT INTO tasks (id, context_id, seq, title, description, status, priority, created_at, updated_at)
                 VALUES (?1, ?2, ?3, ?4, ?5, 'pending', ?6, ?7, ?8)",
                params![id, context_id, seq, title, description, priority, now, now],
            )
            .with_context(|| format!("Failed to insert task '{title}'"))?;

        Ok(Task {
            id,
            context_id,
            seq,
            title: title.to_string(),
            description: description.map(str::to_string),
            status: "pending".to_string(),
            priority: priority.to_string(),
            created_at: now.clone(),
            updated_at: now,
        })
    }

    /// Update non-None fields of a task identified by (context_name, seq).
    pub fn update_task(
        &self,
        context_name: &str,
        seq: i64,
        title: Option<&str>,
        description: Option<&str>,
        status: Option<&str>,
        priority: Option<&str>,
    ) -> Result<Task> {
        let task = self.get_task(context_name, seq)?;
        let now = Utc::now().to_rfc3339();

        let new_title = title.unwrap_or(&task.title);
        // description: if caller passes Some("") we treat it as explicit clear;
        // None means "leave unchanged"
        let new_description: Option<&str> = match description {
            Some(d) => Some(d),
            None => task.description.as_deref(),
        };
        let new_status = status.unwrap_or(&task.status);
        let new_priority = priority.unwrap_or(&task.priority);

        self.db
            .conn()
            .execute(
                "UPDATE tasks SET title = ?1, description = ?2, status = ?3, priority = ?4, updated_at = ?5
                 WHERE id = ?6",
                params![new_title, new_description, new_status, new_priority, now, task.id],
            )
            .with_context(|| format!("Failed to update task {seq} in context '{context_name}'"))?;

        Ok(Task {
            id: task.id,
            context_id: task.context_id,
            seq: task.seq,
            title: new_title.to_string(),
            description: new_description.map(str::to_string),
            status: new_status.to_string(),
            priority: new_priority.to_string(),
            created_at: task.created_at,
            updated_at: now,
        })
    }

    /// Retrieve a task by (context_name, seq).
    pub fn get_task(&self, context_name: &str, seq: i64) -> Result<Task> {
        let context_id = self.lookup_context_id(context_name)?;

        let task = self
            .db
            .conn()
            .query_row(
                "SELECT id, context_id, seq, title, description,
                        status, priority, created_at, updated_at
                 FROM tasks
                 WHERE context_id = ?1 AND seq = ?2",
                params![context_id, seq],
                |row| {
                    Ok(Task {
                        id: row.get(0)?,
                        context_id: row.get(1)?,
                        seq: row.get(2)?,
                        title: row.get(3)?,
                        description: row.get(4)?,
                        status: row.get(5)?,
                        priority: row.get(6)?,
                        created_at: row.get(7)?,
                        updated_at: row.get(8)?,
                    })
                },
            )
            .optional()
            .with_context(|| format!("Failed to query task {seq} in context '{context_name}'"))?
            .ok_or_else(|| {
                anyhow::anyhow!("task {} not found in context '{}'", seq, context_name)
            })?;

        Ok(task)
    }

    /// Retrieve a task together with all its todos.
    pub fn get_full_task(&self, context_name: &str, seq: i64) -> Result<FullTask> {
        let task = self.get_task(context_name, seq)?;
        let todos = self.get_todos(&task.id)?;
        Ok(FullTask { task, todos })
    }

    /// List all tasks in a context ordered by seq.
    pub fn list_tasks(&self, context_name: &str) -> Result<Vec<Task>> {
        let context_id = self.lookup_context_id(context_name)?;

        let mut stmt = self
            .db
            .conn()
            .prepare(
                "SELECT id, context_id, seq, title, description,
                        status, priority, created_at, updated_at
                 FROM tasks
                 WHERE context_id = ?1
                 ORDER BY seq",
            )
            .context("Failed to prepare list_tasks statement")?;

        let tasks = stmt
            .query_map(params![context_id], |row| {
                Ok(Task {
                    id: row.get(0)?,
                    context_id: row.get(1)?,
                    seq: row.get(2)?,
                    title: row.get(3)?,
                    description: row.get(4)?,
                    status: row.get(5)?,
                    priority: row.get(6)?,
                    created_at: row.get(7)?,
                    updated_at: row.get(8)?,
                })
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;

        Ok(tasks)
    }

    /// Add a todo item to a task identified by (context_name, task_seq).
    pub fn add_todo(&self, context_name: &str, task_seq: i64, text: &str) -> Result<TaskTodo> {
        let task = self.get_task(context_name, task_seq)?;
        let now = Utc::now().to_rfc3339();
        let id = Uuid::new_v4().to_string();

        let seq: i64 = self
            .db
            .conn()
            .query_row(
                "SELECT COALESCE(MAX(seq), 0) + 1 FROM task_todos WHERE task_id = ?1",
                params![task.id],
                |row| row.get(0),
            )
            .with_context(|| format!("Failed to determine next todo seq for task {task_seq}"))?;

        self.db
            .conn()
            .execute(
                "INSERT INTO task_todos (id, task_id, seq, text, done, created_at)
                 VALUES (?1, ?2, ?3, ?4, 0, ?5)",
                params![id, task.id, seq, text, now],
            )
            .with_context(|| format!("Failed to insert todo for task {task_seq}"))?;

        Ok(TaskTodo {
            id,
            task_id: task.id,
            seq,
            text: text.to_string(),
            done: false,
            created_at: now,
        })
    }

    /// Mark a todo item as done.
    pub fn mark_todo_done(&self, context_name: &str, task_seq: i64, todo_seq: i64) -> Result<()> {
        let task = self.get_task(context_name, task_seq)?;

        let rows = self
            .db
            .conn()
            .execute(
                "UPDATE task_todos SET done = 1 WHERE task_id = ?1 AND seq = ?2",
                params![task.id, todo_seq],
            )
            .with_context(|| {
                format!("Failed to mark todo {todo_seq} done on task {task_seq} in context '{context_name}'")
            })?;

        if rows == 0 {
            anyhow::bail!(
                "todo {todo_seq} not found on task {task_seq} in context '{context_name}'"
            );
        }

        Ok(())
    }

    /// Retrieve all todos for a task by its id, ordered by seq.
    pub fn get_todos(&self, task_id: &str) -> Result<Vec<TaskTodo>> {
        let mut stmt = self
            .db
            .conn()
            .prepare(
                "SELECT id, task_id, seq, text, done, created_at
                 FROM task_todos
                 WHERE task_id = ?1
                 ORDER BY seq",
            )
            .context("Failed to prepare get_todos statement")?;

        let todos = stmt
            .query_map(params![task_id], |row| {
                let done_int: i64 = row.get(4)?;
                Ok(TaskTodo {
                    id: row.get(0)?,
                    task_id: row.get(1)?,
                    seq: row.get(2)?,
                    text: row.get(3)?,
                    done: done_int != 0,
                    created_at: row.get(5)?,
                })
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;

        Ok(todos)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::db::SCHEMA;
    use rusqlite::Connection;

    fn in_memory_db() -> Database {
        let conn = Connection::open_in_memory().expect("in-memory DB");
        conn.execute_batch(SCHEMA).expect("schema");
        Database::from_parts(conn, std::path::PathBuf::from("/tmp/test"))
    }

    #[test]
    fn test_add_task_seq_increments() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        let t1 = tm
            .add_task("my-context", "First task", None, "medium")
            .unwrap();
        assert_eq!(t1.seq, 1);

        let t2 = tm
            .add_task("my-context", "Second task", None, "high")
            .unwrap();
        assert_eq!(t2.seq, 2);
    }

    #[test]
    fn test_add_task_separate_contexts_have_independent_seqs() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        let t1 = tm.add_task("ctx-a", "Task A1", None, "low").unwrap();
        assert_eq!(t1.seq, 1);

        let t2 = tm.add_task("ctx-b", "Task B1", None, "low").unwrap();
        assert_eq!(t2.seq, 1);

        let t3 = tm.add_task("ctx-a", "Task A2", None, "low").unwrap();
        assert_eq!(t3.seq, 2);
    }

    #[test]
    fn test_update_task_mutates_only_provided_fields() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        tm.add_task("ctx", "Original title", Some("Original desc"), "medium")
            .unwrap();

        // Update only status
        let updated = tm
            .update_task("ctx", 1, None, None, Some("in_progress"), None)
            .unwrap();

        assert_eq!(updated.title, "Original title");
        assert_eq!(updated.description.as_deref(), Some("Original desc"));
        assert_eq!(updated.status, "in_progress");
        assert_eq!(updated.priority, "medium");
    }

    #[test]

    fn test_update_task_not_found_returns_error() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        // Ensure the context exists so we exercise the "task not found" path
        tm.add_task("ctx", "A task", None, "medium").unwrap();

        let result = tm.update_task("ctx", 99, None, None, None, None);
        assert!(result.is_err());
        let msg = result.unwrap_err().to_string();
        assert!(
            msg.contains("task") && msg.contains("not found"),
            "error should mention task not found: {msg}"
        );
    }

    #[test]
    fn test_add_todo_increments_seq() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        tm.add_task("ctx", "A task", None, "medium").unwrap();

        let td1 = tm.add_todo("ctx", 1, "First step").unwrap();
        assert_eq!(td1.seq, 1);

        let td2 = tm.add_todo("ctx", 1, "Second step").unwrap();
        assert_eq!(td2.seq, 2);
    }

    #[test]
    fn test_mark_todo_done_flips_done() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        tm.add_task("ctx", "A task", None, "medium").unwrap();
        tm.add_todo("ctx", 1, "Do something").unwrap();

        // Before marking done
        let full = tm.get_full_task("ctx", 1).unwrap();
        assert!(!full.todos[0].done);

        tm.mark_todo_done("ctx", 1, 1).unwrap();

        let full = tm.get_full_task("ctx", 1).unwrap();
        assert!(full.todos[0].done);
    }

    #[test]
    fn test_mark_todo_done_nonexistent_returns_error() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        tm.add_task("ctx", "A task", None, "medium").unwrap();

        let result = tm.mark_todo_done("ctx", 1, 99);
        assert!(result.is_err());
    }

    #[test]
    fn test_list_tasks_ordered_by_seq() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        tm.add_task("ctx", "C", None, "low").unwrap();
        tm.add_task("ctx", "A", None, "low").unwrap();
        tm.add_task("ctx", "B", None, "low").unwrap();

        let tasks = tm.list_tasks("ctx").unwrap();
        assert_eq!(tasks.len(), 3);
        assert_eq!(tasks[0].seq, 1);
        assert_eq!(tasks[1].seq, 2);
        assert_eq!(tasks[2].seq, 3);
    }

    #[test]
    fn test_get_full_task_includes_todos() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        tm.add_task("ctx", "My task", Some("Details"), "high")
            .unwrap();
        tm.add_todo("ctx", 1, "Step one").unwrap();
        tm.add_todo("ctx", 1, "Step two").unwrap();

        let full = tm.get_full_task("ctx", 1).unwrap();
        assert_eq!(full.task.title, "My task");
        assert_eq!(full.todos.len(), 2);
        assert_eq!(full.todos[0].text, "Step one");
        assert_eq!(full.todos[1].text, "Step two");
    }

    #[test]
    fn test_get_task_nonexistent_context_reports_context_not_found() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        let result = tm.get_task("no-such-context", 1);
        assert!(result.is_err());
        let msg = result.unwrap_err().to_string();
        assert!(
            msg.contains("context") && msg.contains("not found"),
            "error should mention context not found: {msg}"
        );
    }

    #[test]
    fn test_get_task_nonexistent_seq_reports_task_not_found() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        // Create the context via add_task, then query a seq that doesn't exist
        tm.add_task("ctx", "A task", None, "medium").unwrap();

        let result = tm.get_task("ctx", 99);
        assert!(result.is_err());
        let msg = result.unwrap_err().to_string();
        assert!(
            msg.contains("task") && msg.contains("not found"),
            "error should mention task not found: {msg}"
        );
    }

    #[test]
    fn test_list_tasks_nonexistent_context_reports_context_not_found() {
        let db = in_memory_db();
        let tm = TaskManager::new(&db);

        let result = tm.list_tasks("ghost-context");
        assert!(result.is_err());
        let msg = result.unwrap_err().to_string();
        assert!(
            msg.contains("context") && msg.contains("not found"),
            "error should mention context not found: {msg}"
        );
    }
}