package engineeringdashboard

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"strings"
	"time"
)

// ReadyEndpoint maps an environment name to a loopback readiness URL.
type ReadyEndpoint struct {
	Env string
	URL string
}

var defaultReadyEndpoints = []ReadyEndpoint{
	{Env: "dev", URL: "http://127.0.0.1:8080/ready"},
	{Env: "test", URL: "http://127.0.0.1:8081/ready"},
	{Env: "main", URL: "http://127.0.0.1:8000/ready"},
}

var allowedComposeProjects = map[string]string{
	"agent-dev":  "dev",
	"agent-test": "test",
	"agent-main": "main",
	"agent-infra": "shared",
}

// RuntimeCollectResult is the runtime collector output.
type RuntimeCollectResult struct {
	Source       SourceState
	Environments []EnvironmentState
	Facts        []Fact
	Warnings     []string
}

// CollectRuntime gathers docker + readiness + receipt observations.
func CollectRuntime(ctx context.Context, repoRoot string, runner CommandRunner, now time.Time) RuntimeCollectResult {
	start := time.Now()
	res := RuntimeCollectResult{}
	if runner == nil {
		runner = ExecRunner{}
	}

	envs := map[string]*EnvironmentState{
		"shared": {Name: "shared"},
		"dev":    {Name: "dev"},
		"test":   {Name: "test"},
		"main":   {Name: "main"},
	}

	psOut, stderr, err := runner.Run(ctx, repoRoot, "docker", "ps", "-a", "--format", "{{json .}}")
	if err != nil {
		res.Warnings = append(res.Warnings, "docker unavailable: "+strings.TrimSpace(stderr+" "+err.Error()))
		for _, e := range envs {
			e.Facets = DeploymentFacets{
				ContainerStatus: "unknown", AppReadiness: "unknown", ServicesOK: "unknown",
				IdentityNote: "docker unavailable",
			}
		}
	} else {
		for _, line := range strings.Split(psOut, "\n") {
			line = strings.TrimSpace(line)
			if line == "" {
				continue
			}
			cv, envName, ok := parseDockerLine(line)
			if !ok {
				continue
			}
			e := envs[envName]
			if e == nil {
				continue
			}
			e.Containers = append(e.Containers, cv)
		}
	}

	client := &http.Client{
		Timeout: 2 * time.Second,
		CheckRedirect: func(req *http.Request, via []*http.Request) error {
			if err := assertLoopbackReadyURL(req.URL.String()); err != nil {
				return err
			}
			if len(via) >= 3 {
				return fmt.Errorf("too many redirects")
			}
			return nil
		},
	}
	for _, ep := range defaultReadyEndpoints {
		if err := assertLoopbackReadyURL(ep.URL); err != nil {
			res.Warnings = append(res.Warnings, err.Error())
			continue
		}
		status, body, err := getReady(ctx, client, ep.URL)
		e := envs[ep.Env]
		if e == nil {
			continue
		}
		if err != nil {
			e.Readiness = "error"
			e.Facets.AppReadiness = "error"
			res.Warnings = append(res.Warnings, ep.Env+" ready: "+err.Error())
			continue
		}
		if status >= 200 && status < 300 {
			e.Readiness = "ok"
			e.Facets.AppReadiness = "ok"
		} else {
			e.Readiness = fmt.Sprintf("http_%d", status)
			e.Facets.AppReadiness = e.Readiness
		}
		if strings.Contains(body, "schema_version") {
			e.Schema = extractJSONField(body, "schema_version")
		}
		res.Facts = append(res.Facts, Fact{
			ID: FactID("env:"+ep.Env, "readiness", "ready"), Subject: "env:" + ep.Env, Field: "readiness",
			Value: e.Readiness, Provenance: ProvenanceObserved, SourceRef: ep.URL, ObservedAt: now,
		})
	}

	for name, e := range envs {
		e.Facets.ContainerStatus = summarizeContainers(e.Containers)
		e.Facets.ServicesOK = summarizeServices(e.Containers, e.Facets.AppReadiness)
		if e.Facets.AppReadiness == "" {
			e.Facets.AppReadiness = "unknown"
		}
		receipt := findLatestReceipt(repoRoot)
		if receipt != "" {
			e.Receipt = receipt
			e.Facets.ArtifactID = filepath.Base(receipt)
		}
		if e.Facets.ContainerStatus == "partial" && e.Facets.AppReadiness == "ok" {
			e.DriftNotes = append(e.DriftNotes, "app readiness ok coexists with partial container health — no aggregate green")
			e.Facets.IdentityNote = "running visible; service completeness partial"
		}
		if e.Facets.ContainerStatus != "unknown" && e.Facets.ArtifactID == "" {
			e.Facets.IdentityNote = "running visible, version unverified"
		}
		res.Facts = append(res.Facts, Fact{
			ID: FactID("env:"+name, "container_status", "docker"), Subject: "env:" + name, Field: "container_status",
			Value: e.Facets.ContainerStatus, Provenance: ProvenanceObserved, SourceRef: "docker", ObservedAt: now,
		})
	}

	for _, name := range []string{"shared", "dev", "test", "main"} {
		res.Environments = append(res.Environments, *envs[name])
	}

	status := SourceOK
	fresh := FreshnessFresh
	if len(res.Warnings) > 0 {
		status = SourceDegraded
	}
	res.Source = SourceState{
		Name: "runtime", Status: status, Freshness: fresh,
		ObservedAt: now, LastSuccessAt: &now, DurationMS: time.Since(start).Milliseconds(),
	}
	return res
}

func parseDockerLine(line string) (ContainerView, string, bool) {
	var raw map[string]any
	if err := json.Unmarshal([]byte(line), &raw); err != nil {
		return ContainerView{}, "", false
	}
	// docker --format {{json .}} fields vary; support both Names and names
	name := strField(raw, "Names", "names", "Name")
	image := strField(raw, "Image", "image")
	status := strField(raw, "Status", "status", "State")
	labels := strField(raw, "Labels", "labels")
	project, service := parseComposeLabels(labels)
	envName := allowedComposeProjects[project]
	if envName == "" {
		// try infer from name
		lname := strings.ToLower(name)
		switch {
		case strings.Contains(lname, "-dev"), strings.Contains(lname, "_dev"):
			envName = "dev"
		case strings.Contains(lname, "-test"), strings.Contains(lname, "_test"):
			envName = "test"
		case strings.Contains(lname, "-main"), strings.Contains(lname, "_main"):
			envName = "main"
		default:
			return ContainerView{}, "", false
		}
	}
	health := ""
	lowerStatus := strings.ToLower(status)
	switch {
	case strings.Contains(lowerStatus, "unhealthy"):
		health = "unhealthy"
	case strings.Contains(lowerStatus, "healthy"):
		health = "healthy"
	case strings.Contains(lowerStatus, "restarting"):
		health = "unhealthy"
	}
	restarts := 0
	if strings.Contains(lowerStatus, "restarting") {
		restarts = 1
	}
	cv := ContainerView{
		Name: name, Image: image, Status: status, Health: health,
		RestartCount: restarts, Project: project, Service: service,
	}
	return cv, envName, true
}

func strField(m map[string]any, keys ...string) string {
	for _, k := range keys {
		if v, ok := m[k]; ok {
			switch t := v.(type) {
			case string:
				return t
			default:
				return fmt.Sprint(t)
			}
		}
	}
	return ""
}

func parseComposeLabels(labels string) (project, service string) {
	for _, part := range strings.Split(labels, ",") {
		kv := strings.SplitN(part, "=", 2)
		if len(kv) != 2 {
			continue
		}
		switch kv[0] {
		case "com.docker.compose.project":
			project = kv[1]
		case "com.docker.compose.service":
			service = kv[1]
		}
	}
	return project, service
}

func summarizeContainers(cs []ContainerView) string {
	if len(cs) == 0 {
		return "unknown"
	}
	bad := 0
	for _, c := range cs {
		ls := strings.ToLower(c.Status + " " + c.Health)
		if strings.Contains(ls, "restart") || strings.Contains(ls, "unhealthy") || strings.Contains(ls, "exited") {
			bad++
		}
	}
	if bad == 0 {
		return "ok"
	}
	if bad < len(cs) {
		return "partial"
	}
	return "unhealthy"
}

func summarizeServices(cs []ContainerView, readiness string) string {
	cstat := summarizeContainers(cs)
	if cstat == "ok" && readiness == "ok" {
		return "complete"
	}
	if cstat == "unknown" && (readiness == "" || readiness == "unknown") {
		return "unknown"
	}
	if cstat == "partial" || readiness == "ok" {
		return "partial"
	}
	return "partial"
}

func assertLoopbackReadyURL(raw string) error {
	u, err := url.Parse(raw)
	if err != nil {
		return err
	}
	if u.Scheme != "http" && u.Scheme != "https" {
		return fmt.Errorf("ready scheme denied: %s", u.Scheme)
	}
	host := u.Hostname()
	ip := net.ParseIP(host)
	if ip == nil || !ip.IsLoopback() {
		return fmt.Errorf("ready host must be loopback: %s", host)
	}
	port := u.Port()
	switch port {
	case "8080", "8081", "8000", "":
		// ok (empty only if default — still require explicit in our list)
	default:
		return fmt.Errorf("ready port not allowlisted: %s", port)
	}
	return nil
}

func getReady(ctx context.Context, client *http.Client, rawURL string) (int, string, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, rawURL, nil)
	if err != nil {
		return 0, "", err
	}
	resp, err := client.Do(req)
	if err != nil {
		return 0, "", err
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
	return resp.StatusCode, string(body), nil
}

func extractJSONField(body, key string) string {
	var m map[string]any
	if err := json.Unmarshal([]byte(body), &m); err != nil {
		return ""
	}
	if v, ok := m[key]; ok {
		return fmt.Sprint(v)
	}
	return ""
}

func findLatestReceipt(repoRoot string) string {
	dir := filepath.Join(repoRoot, ".doc", "test-reports", "assets", "promotion-receipts")
	entries, err := os.ReadDir(dir)
	if err != nil {
		return ""
	}
	var latest string
	var latestMod time.Time
	for _, e := range entries {
		if e.IsDir() || !strings.HasSuffix(e.Name(), ".json") {
			continue
		}
		info, err := e.Info()
		if err != nil {
			continue
		}
		if info.ModTime().After(latestMod) {
			latestMod = info.ModTime()
			latest = filepath.ToSlash(filepath.Join(".doc/test-reports/assets/promotion-receipts", e.Name()))
		}
	}
	return latest
}