package httpapi

import (
	"context"
	"errors"
	"testing"

	"github.com/wangjia/pangolin/server/internal/nodes"
)

type fakeLoadReader struct {
	load *nodes.NodeLoad
	ok   bool
	err  error
}

func (f fakeLoadReader) Get(context.Context, string) (*nodes.NodeLoad, bool, error) {
	return f.load, f.ok, f.err
}

// TestDataPlaneHealthy: unknown (nil reader / missing / error) defaults to healthy
// (agent liveness gates); a present load returns its reported flag.
func TestDataPlaneHealthy(t *testing.T) {
	ctx := context.Background()
	cases := []struct {
		name string
		api  *NodeAPI
		want bool
	}{
		{"nil reader → healthy", &NodeAPI{}, true},
		{"missing load → healthy", &NodeAPI{load: fakeLoadReader{ok: false}}, true},
		{"read error → healthy", &NodeAPI{load: fakeLoadReader{err: errors.New("boom")}}, true},
		{"present healthy", &NodeAPI{load: fakeLoadReader{load: &nodes.NodeLoad{DataPlaneHealthy: true}, ok: true}}, true},
		{"present unhealthy → false", &NodeAPI{load: fakeLoadReader{load: &nodes.NodeLoad{DataPlaneHealthy: false}, ok: true}}, false},
	}
	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			if got := c.api.dataPlaneHealthy(ctx, "n1"); got != c.want {
				t.Errorf("dataPlaneHealthy = %v, want %v", got, c.want)
			}
		})
	}
}

// TestEffectiveNodeStatus guards the "don't show a node healthy when it can't
// serve" fix: a DB-'up' node reports "down" when its agent is offline OR its data
// plane (sing-box) is unhealthy.
func TestEffectiveNodeStatus(t *testing.T) {
	cases := []struct {
		name    string
		db      string
		online  bool
		healthy bool
		want    string
	}{
		{"up + agent online + healthy", "up", true, true, "up"},
		{"up + agent offline → down", "up", false, true, "down"},          // agent-liveness fix
		{"up + agent online + dp unhealthy → down", "up", true, false, "down"}, // data-plane fix
		{"up + offline + unhealthy → down", "up", false, false, "down"},
		{"draining untouched", "draining", false, false, "draining"},
		{"down stays down", "down", true, true, "down"},
	}
	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			if got := effectiveNodeStatus(c.db, c.online, c.healthy); got != c.want {
				t.Errorf("effectiveNodeStatus(%q, %v, %v) = %q, want %q", c.db, c.online, c.healthy, got, c.want)
			}
		})
	}
}