package handlers

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"net/http"
	"strings"

	"aamos-admin/models"
)

var moduleOrder = []string{
	"academy", "finance", "compliance", "people", "operations",
	"commerce", "identity", "connect", "governance", "analytics",
}

var moduleSeed = []models.Module{
	{ID: "academy", Name: "Academy", Description: "Learning & Training Platform", Icon: "graduation-cap", Status: models.ModuleStatusStopped},
	{ID: "finance", Name: "Finance", Description: "Financial Management & Reporting", Icon: "chart-line", Status: models.ModuleStatusStopped},
	{ID: "compliance", Name: "Compliance", Description: "Regulatory Compliance & Auditing", Icon: "shield-check", Status: models.ModuleStatusStopped},
	{ID: "people", Name: "People", Description: "HR & People Management", Icon: "users", Status: models.ModuleStatusStopped},
	{ID: "operations", Name: "Operations", Description: "Operations & Process Management", Icon: "cogs", Status: models.ModuleStatusStopped},
	{ID: "commerce", Name: "Commerce", Description: "Sales & Commerce Platform", Icon: "shopping-cart", Status: models.ModuleStatusStopped},
	{ID: "identity", Name: "Identity", Description: "Identity & Access Management", Icon: "fingerprint", Status: models.ModuleStatusStopped},
	{ID: "connect", Name: "Connect", Description: "Communications & Integration Hub", Icon: "network-wired", Status: models.ModuleStatusStopped},
	{ID: "governance", Name: "Governance", Description: "Corporate Governance & Policy", Icon: "landmark", Status: models.ModuleStatusStopped},
	{ID: "analytics", Name: "Analytics", Description: "Data Analytics & Business Intelligence", Icon: "chart-bar", Status: models.ModuleStatusStopped},
}

// ModulesHandler handles GET /api/v1/modules and PUT /api/v1/modules/{id}/toggle.
type ModulesHandler struct {
	db *sql.DB
}

// NewModulesHandler seeds the 10 Ouroboros modules (idempotent) and returns the handler.
func NewModulesHandler(db *sql.DB) (*ModulesHandler, error) {
	h := &ModulesHandler{db: db}
	if err := h.seed(); err != nil {
		return nil, fmt.Errorf("modules seed: %w", err)
	}
	return h, nil
}

func (h *ModulesHandler) seed() error {
	for _, m := range moduleSeed {
		_, err := h.db.Exec(
			`INSERT INTO modules (id, name, enabled, description, icon, status)
			 VALUES ($1, $2, FALSE, $3, $4, $5)
			 ON CONFLICT (id) DO NOTHING`,
			m.ID, m.Name, m.Description, m.Icon, string(m.Status),
		)
		if err != nil {
			return fmt.Errorf("seed %s: %w", m.ID, err)
		}
	}
	return nil
}

// List handles GET /api/v1/modules — returns all 10 modules in canonical Ouroboros order.
func (h *ModulesHandler) List(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}

	rows, err := h.db.Query(
		`SELECT id, name, enabled, description, icon, status FROM modules`,
	)
	if err != nil {
		http.Error(w, fmt.Sprintf("db query: %v", err), http.StatusInternalServerError)
		return
	}
	defer rows.Close()

	byID := make(map[string]models.Module, len(moduleOrder))
	for rows.Next() {
		var m models.Module
		var status string
		if err := rows.Scan(&m.ID, &m.Name, &m.Enabled, &m.Description, &m.Icon, &status); err != nil {
			http.Error(w, fmt.Sprintf("db scan: %v", err), http.StatusInternalServerError)
			return
		}
		m.Status = models.ModuleStatus(status)
		byID[m.ID] = m
	}
	if err := rows.Err(); err != nil {
		http.Error(w, fmt.Sprintf("db rows: %v", err), http.StatusInternalServerError)
		return
	}

	result := make([]models.Module, 0, len(moduleOrder))
	for _, id := range moduleOrder {
		if m, ok := byID[id]; ok {
			result = append(result, m)
		}
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(result)
}

// Toggle handles PUT /api/v1/modules/{id}/toggle — flips enabled and syncs status.
func (h *ModulesHandler) Toggle(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPut {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}

	// Extract {id} from /api/v1/modules/{id}/toggle
	parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
	if len(parts) < 2 || parts[len(parts)-1] != "toggle" {
		http.Error(w, "invalid path", http.StatusBadRequest)
		return
	}
	id := parts[len(parts)-2]
	if id == "" || id == "modules" {
		http.Error(w, "missing module id", http.StatusBadRequest)
		return
	}

	// SET expressions use original row values, so NOT enabled correctly toggles:
	// false → true + 'running', true → false + 'stopped'.
	var m models.Module
	var status string
	err := h.db.QueryRow(
		`UPDATE modules
		 SET enabled = NOT enabled,
		     status  = CASE WHEN NOT enabled THEN $2 ELSE $3 END
		 WHERE id = $1
		 RETURNING id, name, enabled, description, icon, status`,
		id,
		string(models.ModuleStatusRunning),
		string(models.ModuleStatusStopped),
	).Scan(&m.ID, &m.Name, &m.Enabled, &m.Description, &m.Icon, &status)

	if err == sql.ErrNoRows {
		http.Error(w, "module not found", http.StatusNotFound)
		return
	}
	if err != nil {
		http.Error(w, fmt.Sprintf("db update: %v", err), http.StatusInternalServerError)
		return
	}
	m.Status = models.ModuleStatus(status)

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(m)
}