package app

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"strconv"
	"strings"
	"time"
)

func (s *Server) handlePortal(w http.ResponseWriter, r *http.Request) {
	tech, err := s.currentTechnician(r)
	if err != nil {
		http.Redirect(w, r, "/", http.StatusSeeOther)
		return
	}
	packages, err := s.listPackages(r)
	if err != nil {
		http.Error(w, "unable to list packages", http.StatusInternalServerError)
		return
	}
	authorizations, err := s.listAuthorizations(r)
	if err != nil {
		http.Error(w, "unable to list authorizations", http.StatusInternalServerError)
		return
	}
	auditEvents, err := s.listAuditEvents(r)
	if err != nil {
		http.Error(w, "unable to list audit events", http.StatusInternalServerError)
		return
	}
	s.render(w, "portal.html", pageData{
		Title:            "Deployment Access",
		Technician:       tech,
		CSRFToken:        tech.CSRFToken,
		Authorizations:   authorizations,
		AuditEvents:      auditEvents,
		Packages:         packages,
		NewCode:          r.URL.Query().Get("code"),
		DefaultHostLimit: s.cfg.DefaultHostLimit,
		DefaultDuration:  strconv.Itoa(int(s.cfg.DefaultDuration.Hours())),
		Notice:           r.URL.Query().Get("notice"),
	})
}

func (s *Server) listAuditEvents(r *http.Request) ([]auditRecord, error) {
	rows, err := s.db.QueryContext(
		r.Context(),
		`SELECT event_type, actor, hostname, package_slug, source_ip, details, created_at
		   FROM audit_events
		  ORDER BY created_at DESC
		  LIMIT 100`,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var records []auditRecord
	for rows.Next() {
		var record auditRecord
		if err := rows.Scan(
			&record.EventType,
			&record.Actor,
			&record.Hostname,
			&record.PackageSlug,
			&record.SourceIP,
			&record.Details,
			&record.CreatedAt,
		); err != nil {
			return nil, err
		}
		records = append(records, record)
	}
	return records, rows.Err()
}

func (s *Server) listPackages(r *http.Request) ([]packageRecord, error) {
	rows, err := s.db.QueryContext(
		r.Context(),
		`SELECT id, slug, display_name, package_name, package_version,
		        file_name, sha256, enabled
		   FROM packages
		  ORDER BY display_name, package_version`,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var records []packageRecord
	for rows.Next() {
		var record packageRecord
		if err := rows.Scan(
			&record.ID,
			&record.Slug,
			&record.DisplayName,
			&record.PackageName,
			&record.PackageVersion,
			&record.FileName,
			&record.SHA256,
			&record.Enabled,
		); err != nil {
			return nil, err
		}
		records = append(records, record)
	}
	return records, rows.Err()
}

func (s *Server) listAuthorizations(r *http.Request) ([]authorizationRecord, error) {
	rows, err := s.db.QueryContext(
		r.Context(),
		`SELECT a.id, a.code_hint, a.created_by, a.customer_label,
		        a.host_limit, COUNT(DISTINCT h.id), a.created_at,
		        a.expires_at, a.revoked_at,
		        COALESCE(GROUP_CONCAT(DISTINCT p.display_name
		          ORDER BY p.display_name SEPARATOR ', '), '')
		   FROM authorizations a
		   LEFT JOIN authorization_hosts h ON h.authorization_id = a.id
		   LEFT JOIN authorization_packages ap ON ap.authorization_id = a.id
		   LEFT JOIN packages p ON p.id = ap.package_id
		  WHERE a.created_at > UTC_TIMESTAMP(6) - INTERVAL 30 DAY
		  GROUP BY a.id
		  ORDER BY a.created_at DESC
		  LIMIT 100`,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var records []authorizationRecord
	for rows.Next() {
		var record authorizationRecord
		if err := rows.Scan(
			&record.ID,
			&record.CodeHint,
			&record.CreatedBy,
			&record.CustomerLabel,
			&record.HostLimit,
			&record.HostCount,
			&record.CreatedAt,
			&record.ExpiresAt,
			&record.RevokedAt,
			&record.Packages,
		); err != nil {
			return nil, err
		}
		records = append(records, record)
	}
	return records, rows.Err()
}

func (s *Server) handleCreateAuthorization(w http.ResponseWriter, r *http.Request) {
	tech, _ := s.currentTechnician(r)
	hostLimit, err := strconv.Atoi(r.FormValue("host_limit"))
	if err != nil || hostLimit < 1 || hostLimit > s.cfg.MaxHostLimit {
		http.Error(w, "invalid host limit", http.StatusBadRequest)
		return
	}
	durationHours, err := strconv.Atoi(r.FormValue("duration_hours"))
	if err != nil || durationHours < 1 || durationHours > 24 {
		http.Error(w, "duration must be between 1 and 24 hours", http.StatusBadRequest)
		return
	}
	packageIDs := r.Form["package_id"]
	if len(packageIDs) == 0 {
		http.Error(w, "select at least one package", http.StatusBadRequest)
		return
	}
	code, err := deploymentCode()
	if err != nil {
		http.Error(w, "unable to generate code", http.StatusInternalServerError)
		return
	}
	codeHash := hashValue(code)
	expiresAt := time.Now().UTC().Add(time.Duration(durationHours) * time.Hour)
	customerLabel := strings.TrimSpace(r.FormValue("customer_label"))
	if len(customerLabel) > 255 {
		http.Error(w, "customer label is too long", http.StatusBadRequest)
		return
	}

	tx, err := s.db.BeginTx(r.Context(), nil)
	if err != nil {
		http.Error(w, "unable to create authorization", http.StatusInternalServerError)
		return
	}
	defer tx.Rollback()
	result, err := tx.ExecContext(
		r.Context(),
		`INSERT INTO authorizations
			(code_hash, code_hint, created_by, customer_label, host_limit, expires_at)
		 VALUES (?, ?, ?, ?, ?, ?)`,
		codeHash[:], code[len(code)-5:], tech.Login, customerLabel, hostLimit, expiresAt,
	)
	if err != nil {
		http.Error(w, "unable to create authorization", http.StatusInternalServerError)
		return
	}
	authorizationID, _ := result.LastInsertId()
	for _, rawID := range packageIDs {
		packageID, err := strconv.ParseUint(rawID, 10, 64)
		if err != nil {
			http.Error(w, "invalid package selection", http.StatusBadRequest)
			return
		}
		result, err := tx.ExecContext(
			r.Context(),
			`INSERT INTO authorization_packages (authorization_id, package_id)
			 SELECT ?, id FROM packages WHERE id = ? AND enabled = TRUE`,
			authorizationID, packageID,
		)
		if err != nil {
			http.Error(w, "unable to authorize package", http.StatusInternalServerError)
			return
		}
		affected, _ := result.RowsAffected()
		if affected != 1 {
			http.Error(w, "selected package is unavailable", http.StatusBadRequest)
			return
		}
	}
	if err := tx.Commit(); err != nil {
		http.Error(w, "unable to save authorization", http.StatusInternalServerError)
		return
	}
	id := uint64(authorizationID)
	_ = s.audit(r.Context(), "authorization_created", tech.Login, &id, "", "", s.clientIP(r),
		fmt.Sprintf("host_limit=%d duration_hours=%d customer=%q", hostLimit, durationHours, customerLabel))
	http.Redirect(w, r, "/portal?code="+code, http.StatusSeeOther)
}

func (s *Server) handleRevokeAuthorization(w http.ResponseWriter, r *http.Request) {
	tech, _ := s.currentTechnician(r)
	id, err := parseUintPath(r, "id")
	if err != nil {
		http.Error(w, "invalid authorization", http.StatusBadRequest)
		return
	}
	result, err := s.db.ExecContext(
		r.Context(),
		`UPDATE authorizations
		    SET revoked_at = COALESCE(revoked_at, UTC_TIMESTAMP(6))
		  WHERE id = ?`,
		id,
	)
	if err != nil {
		http.Error(w, "unable to revoke authorization", http.StatusInternalServerError)
		return
	}
	affected, _ := result.RowsAffected()
	if affected == 0 {
		http.Error(w, "authorization not found", http.StatusNotFound)
		return
	}
	_, _ = s.db.ExecContext(
		r.Context(),
		`UPDATE download_sessions SET revoked_at = UTC_TIMESTAMP(6)
		  WHERE authorization_id = ? AND revoked_at IS NULL`,
		id,
	)
	_ = s.audit(r.Context(), "authorization_revoked", tech.Login, &id, "", "", s.clientIP(r), "")
	http.Redirect(w, r, "/portal?notice=Authorization+revoked", http.StatusSeeOther)
}

func (s *Server) handleUpsertPackage(w http.ResponseWriter, r *http.Request) {
	tech, _ := s.currentTechnician(r)
	fields := []string{
		"slug", "display_name", "package_name", "package_version", "file_name", "sha256",
	}
	values := make(map[string]string)
	for _, field := range fields {
		values[field] = strings.TrimSpace(r.FormValue(field))
		if values[field] == "" {
			http.Error(w, field+" is required", http.StatusBadRequest)
			return
		}
	}
	if !validSlug(values["slug"]) || !validSHA256(values["sha256"]) {
		http.Error(w, "invalid slug or SHA-256", http.StatusBadRequest)
		return
	}
	enabled := r.FormValue("enabled") == "1"
	_, err := s.db.ExecContext(
		r.Context(),
		`INSERT INTO packages
			(slug, display_name, package_name, package_version, file_name, sha256, enabled)
		 VALUES (?, ?, ?, ?, ?, ?, ?)
		 ON DUPLICATE KEY UPDATE
			display_name = VALUES(display_name),
			package_name = VALUES(package_name),
			package_version = VALUES(package_version),
			file_name = VALUES(file_name),
			sha256 = VALUES(sha256),
			enabled = VALUES(enabled)`,
		values["slug"],
		values["display_name"],
		values["package_name"],
		values["package_version"],
		values["file_name"],
		strings.ToLower(values["sha256"]),
		enabled,
	)
	if err != nil {
		http.Error(w, "unable to save package", http.StatusInternalServerError)
		return
	}
	_ = s.audit(r.Context(), "package_saved", tech.Login, nil, "", values["slug"], s.clientIP(r),
		fmt.Sprintf("version=%s enabled=%t", values["package_version"], enabled))
	http.Redirect(w, r, "/portal?notice=Package+saved", http.StatusSeeOther)
}

func validSlug(value string) bool {
	if value == "" || len(value) > 100 {
		return false
	}
	for _, character := range value {
		if (character < 'a' || character > 'z') &&
			(character < '0' || character > '9') &&
			character != '-' && character != '_' {
			return false
		}
	}
	return true
}

func validSHA256(value string) bool {
	if len(value) != 64 {
		return false
	}
	for _, character := range strings.ToLower(value) {
		if (character < '0' || character > '9') &&
			(character < 'a' || character > 'f') {
			return false
		}
	}
	return true
}

func (s *Server) audit(
	ctx context.Context,
	eventType string,
	actor string,
	authorizationID *uint64,
	hostname string,
	packageSlug string,
	sourceIP string,
	details string,
) error {
	var authID any
	if authorizationID != nil {
		authID = *authorizationID
	}
	_, err := s.db.ExecContext(
		ctx,
		`INSERT INTO audit_events
			(event_type, actor, authorization_id, hostname, package_slug, source_ip, details)
		 VALUES (?, ?, ?, ?, ?, ?, ?)`,
		eventType, actor, authID, hostname, packageSlug, sourceIP, details,
	)
	return err
}

var errAuthorizationDenied = errors.New("authorization denied")