package render

import (
	"html/template"
	"net/url"
	"path"
	"strconv"
	"strings"
)

const (
	urlBasePublic = iota
	urlBaseHTTP
	urlBaseGemini
)

// URLBuilder is used to construct a URL for the site. The API of URLBuilder is
// designed to be convenient to used from a go template.
type URLBuilder struct {
	publicURL, httpURL, geminiURL *url.URL

	abs          bool
	base         int
	path, method string
	page         int
}

func NewURLBuilder(publicURL, httpURL, geminiURL *url.URL) URLBuilder {
	return URLBuilder{
		publicURL: publicURL,
		httpURL:   httpURL,
		geminiURL: geminiURL,
	}
}

func (b URLBuilder) String() string {
	var u *url.URL
	switch b.base {
	case urlBasePublic:
		u = b.publicURL
	case urlBaseHTTP:
		u = b.httpURL
	case urlBaseGemini:
		u = b.geminiURL
	}

	u = u.JoinPath(b.path)

	if u.Scheme == "gemini" &&
		u.Host == b.geminiURL.Host &&
		!strings.HasSuffix(u.Path, "/") &&
		path.Ext(u.Path) == "" {
		u.Path += ".gmi"
	}

	{
		query := url.Values{}
		if b.method != "" {
			query.Set("method", b.method)
		}
		if b.page > 0 {
			query.Set("page", strconv.Itoa(b.page))
		}
		if len(query) > 0 {
			u.RawQuery = query.Encode()
		}
	}

	if abs := b.abs || u.Scheme != b.publicURL.Scheme; !abs {
		u.Scheme = ""
		u.Host = ""
	}

	return u.String()
}

func (b URLBuilder) HTMLSafe() template.URL {
	return template.URL(b.String())
}

// Absolute returns a URLBuilder which will always construct a URL containing
// scheme and host.
func (b URLBuilder) Absolute() URLBuilder {
	b.abs = true
	return b
}

func (b URLBuilder) Gemini() URLBuilder {
	b.base = urlBaseGemini
	return b
}

func (b URLBuilder) HTTP() URLBuilder {
	b.base = urlBaseHTTP
	return b
}

func (b URLBuilder) Assets() URLBuilder {
	b.path = "assets/"
	return b
}

func (b URLBuilder) Asset(id string) URLBuilder {
	b.path = "assets/" + id
	return b
}

func (b URLBuilder) Posts() URLBuilder {
	b.path = "posts/"
	return b
}

func (b URLBuilder) Post(id string) URLBuilder {
	b.path = "posts/" + id
	return b
}

func (b URLBuilder) Drafts() URLBuilder {
	b.base = urlBaseHTTP
	b.path = "drafts/"
	return b
}

func (b URLBuilder) Draft(id string) URLBuilder {
	b.base = urlBaseHTTP
	b.path = "drafts/" + id
	return b
}

func (b URLBuilder) Static(staticPath string) URLBuilder {
	b.base = urlBaseHTTP
	b.path = path.Join("static", staticPath)
	return b
}

func (b URLBuilder) Path(p string) URLBuilder {
	b.path = p
	return b
}

func (b URLBuilder) Page(page int) URLBuilder {
	b.page = page
	return b
}

func (b URLBuilder) MethodEdit() URLBuilder {
	b.base = urlBaseHTTP
	b.method = "edit"
	return b
}

func (b URLBuilder) MethodManage() URLBuilder {
	b.base = urlBaseHTTP
	b.method = "manage"
	return b
}

func (b URLBuilder) MethodDelete() URLBuilder {
	b.base = urlBaseHTTP
	b.method = "delete"
	return b
}

func (b URLBuilder) MethodPreview() URLBuilder {
	b.base = urlBaseHTTP
	b.method = "preview"
	return b
}