package store

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

// User is one geniusrun account, bound 1:1 to an OIDC subject. Every
// synced/classified dataset (profile, workout kinds, activities, sync
// state) is scoped to exactly one User -- see
// docs/superpowers/specs/2026-07-25-per-user-profile-design.md.
type User struct {
	ID          int64
	OIDCSub     string
	DisplayName string
	CreatedAt   string
}

// CreateUser inserts a bare users row. Most callers want ProvisionUser
// instead, which also seeds the profile/taxonomy/sync-state a fresh account
// needs; CreateUser alone exists for ClaimLegacyOwner (Task 3), which
// attaches an *existing* profile/taxonomy rather than seeding new ones.
func (db *DB) CreateUser(ctx context.Context, oidcSub, displayName string) (int64, error) {
	res, err := db.ExecContext(ctx, `INSERT INTO users (oidc_sub, display_name) VALUES (?, ?)`, oidcSub, displayName)
	if err != nil {
		return 0, fmt.Errorf("create user %q: %w", oidcSub, err)
	}
	return res.LastInsertId()
}

// GetUserBySub looks up a user by their OIDC subject -- the only lookup key
// the session-resolution middleware (Task 11) ever uses.
func (db *DB) GetUserBySub(ctx context.Context, oidcSub string) (User, bool, error) {
	var u User
	err := db.QueryRowContext(ctx, `SELECT id, oidc_sub, display_name, created_at FROM users WHERE oidc_sub = ?`, oidcSub).
		Scan(&u.ID, &u.OIDCSub, &u.DisplayName, &u.CreatedAt)
	if err == sql.ErrNoRows {
		return User{}, false, nil
	}
	if err != nil {
		return User{}, false, fmt.Errorf("get user by sub: %w", err)
	}
	return u, true, nil
}

// ListUsers returns every provisioned user, for the background incremental
// sync loop (Task 13) to iterate.
func (db *DB) ListUsers(ctx context.Context) ([]User, error) {
	rows, err := db.QueryContext(ctx, `SELECT id, oidc_sub, display_name, created_at FROM users ORDER BY id`)
	if err != nil {
		return nil, fmt.Errorf("list users: %w", err)
	}
	defer rows.Close()

	users := []User{}
	for rows.Next() {
		var u User
		if err := rows.Scan(&u.ID, &u.OIDCSub, &u.DisplayName, &u.CreatedAt); err != nil {
			return nil, fmt.Errorf("scan user row: %w", err)
		}
		users = append(users, u)
	}
	return users, rows.Err()
}

// neverMatchRule is the same placeholder every fresh install's rule-engine
// kinds start with (migration 0004) -- every activity lands in needs_review
// until the user tunes real rules.
const neverMatchRule = `{"match":"all","conditions":[{"metric":"distance_meters","op":"<","value":0}]}`

// defaultWorkoutKindSeeds mirrors the 8 kinds migrations 0004/0007 seed for
// a fresh install, so a newly-provisioned user starts with the same
// taxonomy instead of an empty one.
var defaultWorkoutKindSeeds = []WorkoutKind{
	{Name: "Easy", Color: "#22c55e", RuleJSON: neverMatchRule, Priority: 80, IsActive: true},
	{Name: "Long", Color: "#3b82f6", RuleJSON: neverMatchRule, Priority: 70, IsActive: true},
	{Name: "60' Threshold", Color: "#f59e0b", RuleJSON: neverMatchRule, Priority: 60, IsActive: true},
	{Name: "30' Threshold", Color: "#f59e0b", RuleJSON: neverMatchRule, Priority: 50, IsActive: true},
	{Name: "Tempo", Color: "#eab308", RuleJSON: neverMatchRule, Priority: 40, IsActive: true},
	{Name: "Intervals", Color: "#ef4444", RuleJSON: neverMatchRule, Priority: 30, IsActive: true},
	{Name: "MAS Test", Color: "#a855f7", RuleJSON: neverMatchRule, Priority: 20, IsActive: true},
	{Name: "Race", Color: "#dc2626", RuleJSON: `{"match":"all","conditions":[{"metric":"is_race","op":"==","value":true}]}`, Priority: 10, IsActive: true},
}

// ProvisionUser creates a brand-new geniusrun account for an OIDC subject:
// the users row, a default profile (name defaulted to displayName), the 8
// default workout kinds (with their paired workout_type_paces rows), and an
// initial sync_state row -- all in one transaction, so a partially
// provisioned user is never observable.
func (db *DB) ProvisionUser(ctx context.Context, oidcSub, displayName string) (int64, error) {
	tx, err := db.BeginTx(ctx, nil)
	if err != nil {
		return 0, fmt.Errorf("begin provision user tx: %w", err)
	}
	defer tx.Rollback()

	res, err := tx.ExecContext(ctx, `INSERT INTO users (oidc_sub, display_name) VALUES (?, ?)`, oidcSub, displayName)
	if err != nil {
		return 0, fmt.Errorf("create user %q: %w", oidcSub, err)
	}
	userID, err := res.LastInsertId()
	if err != nil {
		return 0, err
	}

	if _, err := tx.ExecContext(ctx, `INSERT INTO profile (user_id, name) VALUES (?, ?)`, userID, displayName); err != nil {
		return 0, fmt.Errorf("create profile for user %d: %w", userID, err)
	}

	for _, k := range defaultWorkoutKindSeeds {
		res, err := tx.ExecContext(ctx, `
			INSERT INTO workout_kinds (user_id, name, description, color, rule_json, priority, is_active)
			VALUES (?,?,?,?,?,?,?)`,
			userID, k.Name, k.Description, k.Color, k.RuleJSON, k.Priority, k.IsActive)
		if err != nil {
			return 0, fmt.Errorf("seed workout kind %q for user %d: %w", k.Name, userID, err)
		}
		kindID, err := res.LastInsertId()
		if err != nil {
			return 0, err
		}
		if _, err := tx.ExecContext(ctx, `INSERT INTO workout_type_paces (workout_kind_id) VALUES (?)`, kindID); err != nil {
			return 0, fmt.Errorf("seed workout type pace for kind %d: %w", kindID, err)
		}
	}

	if _, err := tx.ExecContext(ctx, `INSERT INTO sync_state (user_id, earliest_synced_date, backfill_complete) VALUES (?, NULL, 0)`, userID); err != nil {
		return 0, fmt.Errorf("create sync state for user %d: %w", userID, err)
	}

	return userID, tx.Commit()
}