package modules

import (
	"context"

	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/kindredsystems/silo/internal/config"
)

// LoadState applies module state from config YAML and database overrides.
//
// Precedence (highest wins):
//  1. Database module_state table
//  2. YAML modules.* toggles
//  3. Backward-compat YAML fields (auth.enabled, odoo.enabled)
//  4. Module defaults (set by NewRegistry)
func LoadState(r *Registry, cfg *config.Config, pool *pgxpool.Pool) error {
	// Step 1: Apply backward-compat top-level YAML fields.
	// auth.enabled and odoo.enabled existed before the modules section.
	// Only apply if the new modules.* section doesn't override them.
	if cfg.Modules.Auth == nil {
		r.setEnabledUnchecked(Auth, cfg.Auth.Enabled)
	}
	if cfg.Modules.Odoo == nil {
		r.setEnabledUnchecked(Odoo, cfg.Odoo.Enabled)
	}

	// Step 2: Apply explicit modules.* YAML toggles (override defaults + compat).
	applyToggle(r, Auth, cfg.Modules.Auth)
	applyToggle(r, Projects, cfg.Modules.Projects)
	applyToggle(r, Audit, cfg.Modules.Audit)
	applyToggle(r, Odoo, cfg.Modules.Odoo)
	applyToggle(r, FreeCAD, cfg.Modules.FreeCAD)
	applyToggle(r, Jobs, cfg.Modules.Jobs)
	applyToggle(r, DAG, cfg.Modules.DAG)

	// Step 3: Apply database overrides (highest precedence).
	if pool != nil {
		if err := loadFromDB(r, pool); err != nil {
			return err
		}
	}

	// Step 4: Validate the final state.
	return r.ValidateDependencies()
}

// applyToggle sets a module's state from a YAML ModuleToggle if present.
func applyToggle(r *Registry, id string, toggle *config.ModuleToggle) {
	if toggle == nil || toggle.Enabled == nil {
		return
	}
	r.setEnabledUnchecked(id, *toggle.Enabled)
}

// setEnabledUnchecked sets module state without dependency validation.
// Used during loading when the full state is being assembled incrementally.
func (r *Registry) setEnabledUnchecked(id string, enabled bool) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if m, ok := r.modules[id]; ok && !m.Required {
		m.enabled = enabled
	}
}

// loadFromDB reads module_state rows and applies them to the registry.
func loadFromDB(r *Registry, pool *pgxpool.Pool) error {
	rows, err := pool.Query(context.Background(),
		`SELECT module_id, enabled FROM module_state`)
	if err != nil {
		return err
	}
	defer rows.Close()

	for rows.Next() {
		var id string
		var enabled bool
		if err := rows.Scan(&id, &enabled); err != nil {
			return err
		}
		r.setEnabledUnchecked(id, enabled)
	}
	return rows.Err()
}