package store

import (
	"context"
	"database/sql"
	"fmt"
)

// migrations are ordered, forward-only schema steps applied after schema.sql.
// Index i (1-based) is the user_version the step at migrations[i-1] brings the
// DB TO; there is no step 0 — schema.sql is the idempotent baseline (version 0).
// An empty slice is a clean no-op that leaves user_version at 0.
//
// To add migration #1 (e.g. the sqlcipher rekey), append its SQL:
//
//	var migrations = []string{
//		`ALTER TABLE ...;`, // #1
//	}
var migrations = []string{
	`ALTER TABLE tools ADD COLUMN scope TEXT NOT NULL DEFAULT 'homelab';`, // #1
	`ALTER TABLE reminders ADD COLUMN cron TEXT;
ALTER TABLE reminders ADD COLUMN next_fire_ts INTEGER;`, // #2
	`CREATE TABLE memory_vectors (
		id         TEXT PRIMARY KEY,
		vec        BLOB NOT NULL,
		meta       TEXT NOT NULL DEFAULT '{}',
		created_ts INTEGER NOT NULL
	);`, // #3 — long-term vector memory (persistent backend for internal/memory)
	`CREATE TABLE IF NOT EXISTS events (
		id         INTEGER PRIMARY KEY AUTOINCREMENT,
		fact_id    INTEGER NOT NULL REFERENCES facts(id),
		action     TEXT NOT NULL,
		object     TEXT NOT NULL,
		ts         INTEGER NOT NULL
	);
	CREATE INDEX IF NOT EXISTS idx_events_action_object ON events (action, object, ts DESC);
	CREATE TABLE IF NOT EXISTS proposed_routines (
		id            INTEGER PRIMARY KEY AUTOINCREMENT,
		action        TEXT NOT NULL,
		object        TEXT NOT NULL,
		interval_days REAL NOT NULL,
		status        TEXT NOT NULL DEFAULT 'proposed' CHECK (status IN ('proposed','accepted','dismissed')),
		created_ts    INTEGER NOT NULL,
		reminder_id   INTEGER REFERENCES reminders(id),
		UNIQUE(action, object)
	);`, // #4 — event extraction + pattern inference

	`CREATE TABLE IF NOT EXISTS ack_sends (
		rule      TEXT NOT NULL,
		sent_at   INTEGER NOT NULL
	);
	CREATE INDEX IF NOT EXISTS idx_ack_sends_rule ON ack_sends (rule, sent_at DESC);`, // #5 — sev4 telegram repeat-til-ack tracking

	`CREATE TABLE IF NOT EXISTS delivery_attempts (
		id           INTEGER PRIMARY KEY AUTOINCREMENT,
		kind         TEXT NOT NULL CHECK (kind IN ('nudge','reminder')),
		rule         TEXT NOT NULL DEFAULT '',
		reminder_id  INTEGER NOT NULL DEFAULT 0,
		channel      TEXT NOT NULL,
		body_hash    TEXT NOT NULL,
		status       TEXT NOT NULL DEFAULT 'pending' CHECK (status IN ('pending','sent','failed','unknown')),
		created_ts   INTEGER NOT NULL,
		completed_ts INTEGER
	);
	CREATE INDEX IF NOT EXISTS idx_delivery_attempts_status ON delivery_attempts (status);`, // #6 — durable delivery outbox

	`ALTER TABLE facts ADD COLUMN subject TEXT NOT NULL DEFAULT '';
	ALTER TABLE facts ADD COLUMN entity_id TEXT;
	ALTER TABLE facts ADD COLUMN resolution_state TEXT NOT NULL DEFAULT 'none'
		CHECK (resolution_state IN ('none','pending','resolved','ambiguous','not_found'));
	CREATE INDEX IF NOT EXISTS idx_facts_entity_id ON facts (entity_id) WHERE entity_id IS NOT NULL;
	CREATE INDEX IF NOT EXISTS idx_facts_resolution_pending ON facts (resolution_state) WHERE resolution_state = 'pending';`, // #7 — entity-aware memory (Vikunja #279): facts about a subject get resolved to a Nexus entity_id async
}

// migrate applies every migration with a number greater than the DB's current
// user_version, each in its own transaction that also bumps user_version. Fails
// closed: the first erroring step aborts and leaves prior steps committed.
func migrate(ctx context.Context, db *sql.DB) error {
	var current int
	if err := db.QueryRowContext(ctx, "PRAGMA user_version").Scan(&current); err != nil {
		return fmt.Errorf("read user_version: %w", err)
	}
	for i := current; i < len(migrations); i++ {
		version := i + 1 // 1-based: migrations[i] brings DB to `version`
		tx, err := db.BeginTx(ctx, nil)
		if err != nil {
			return fmt.Errorf("migration %d begin: %w", version, err)
		}
		if _, err := tx.ExecContext(ctx, migrations[i]); err != nil {
			_ = tx.Rollback()
			return fmt.Errorf("migration %d: %w", version, err)
		}
		// PRAGMA user_version can't be parameterized; version is our own int.
		if _, err := tx.ExecContext(ctx, fmt.Sprintf("PRAGMA user_version = %d", version)); err != nil {
			_ = tx.Rollback()
			return fmt.Errorf("migration %d bump: %w", version, err)
		}
		if err := tx.Commit(); err != nil {
			return fmt.Errorf("migration %d commit: %w", version, err)
		}
	}
	return nil
}