package birdfmt

import (
	"net/netip"
	"sort"
	"strings"
)

// StaticRoute is one static route line in BIRD (optionally with a per-route body).
type StaticRoute struct {
	Prefix    netip.Prefix
	RouteBody string // optional lines inside `route P unreachable { ... }`
}

// RenderStaticIPv4Routes renders a BIRD 2 protocol static block for IPv4.
func RenderStaticIPv4Routes(protocolName string, routes []StaticRoute) string {
	if protocolName == "" {
		protocolName = "evobgp_prefixes_v4"
	}
	type key struct {
		p string
		b string
	}
	uniq := make(map[key]StaticRoute)
	for _, r := range routes {
		if !r.Prefix.Addr().Is4() {
			continue
		}
		p := r.Prefix.Masked()
		body := strings.TrimSpace(r.RouteBody)
		uniq[key{p.String(), body}] = StaticRoute{Prefix: p, RouteBody: body}
	}
	keys := make([]key, 0, len(uniq))
	for k := range uniq {
		keys = append(keys, k)
	}
	sort.Slice(keys, func(i, j int) bool {
		if keys[i].p != keys[j].p {
			return keys[i].p < keys[j].p
		}
		return keys[i].b < keys[j].b
	})

	var b strings.Builder
	b.WriteString("protocol static ")
	b.WriteString(protocolName)
	b.WriteString(" {\n    ipv4;\n")
	for _, k := range keys {
		r := uniq[k]
		p := r.Prefix.String()
		if r.RouteBody == "" {
			b.WriteString("    route ")
			b.WriteString(p)
			b.WriteString(" unreachable;\n")
			continue
		}
		b.WriteString("    route ")
		b.WriteString(p)
		b.WriteString(" unreachable {\n")
		for _, line := range strings.Split(r.RouteBody, "\n") {
			line = strings.TrimRight(line, "\r")
			if strings.TrimSpace(line) == "" {
				continue
			}
			if !strings.HasPrefix(line, "    ") && !strings.HasPrefix(line, "\t") {
				b.WriteString("    ")
			}
			b.WriteString(line)
			b.WriteByte('\n')
		}
		b.WriteString("    };\n")
	}
	b.WriteString("}\n")
	return b.String()
}

// RenderStaticIPv6Routes renders a BIRD 2 protocol static block for IPv6.
func RenderStaticIPv6Routes(protocolName string, routes []StaticRoute) string {
	if protocolName == "" {
		protocolName = "evobgp_prefixes_v6"
	}
	type key struct {
		p string
		b string
	}
	uniq := make(map[key]StaticRoute)
	for _, r := range routes {
		if !r.Prefix.Addr().Is6() {
			continue
		}
		p := r.Prefix.Masked()
		body := strings.TrimSpace(r.RouteBody)
		uniq[key{p.String(), body}] = StaticRoute{Prefix: p, RouteBody: body}
	}
	keys := make([]key, 0, len(uniq))
	for k := range uniq {
		keys = append(keys, k)
	}
	sort.Slice(keys, func(i, j int) bool {
		if keys[i].p != keys[j].p {
			return keys[i].p < keys[j].p
		}
		return keys[i].b < keys[j].b
	})

	var b strings.Builder
	b.WriteString("protocol static ")
	b.WriteString(protocolName)
	b.WriteString(" {\n    ipv6;\n")
	for _, k := range keys {
		r := uniq[k]
		p := r.Prefix.String()
		if r.RouteBody == "" {
			b.WriteString("    route ")
			b.WriteString(p)
			b.WriteString(" unreachable;\n")
			continue
		}
		b.WriteString("    route ")
		b.WriteString(p)
		b.WriteString(" unreachable {\n")
		for _, line := range strings.Split(r.RouteBody, "\n") {
			line = strings.TrimRight(line, "\r")
			if strings.TrimSpace(line) == "" {
				continue
			}
			if !strings.HasPrefix(line, "    ") && !strings.HasPrefix(line, "\t") {
				b.WriteString("    ")
			}
			b.WriteString(line)
			b.WriteByte('\n')
		}
		b.WriteString("    };\n")
	}
	b.WriteString("}\n")
	return b.String()
}