Redirect from http:// to https:// or https://www having CloudFlare Flexible SSL mode
a) Basic http:// to https:// redirection, but this block should be used along with CloudFlare Flexible SSL Mode


RewriteEngine On
RewriteBase /

RewriteCond %{HTTPS} !=on
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteCond %{HTTP_HOST} ^example\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.example\.com$
RewriteRule .* https://example.com%{REQUEST_URI} [R=301,L]

b) The same rule, but redirects to https://www


RewriteEngine On
RewriteBase /

RewriteCond %{HTTPS} !=on
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteCond %{HTTP_HOST} ^example\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.example\.com$
RewriteRule .* https://www.example.com%{REQUEST_URI} [R=301,L]