package web

import (
	"context"
	_ "embed"
	"encoding/json"
	"net/http"
	"os"
	"strings"
	"sync"
	"time"

	cadatlas "git.d-ma.be/mathias/cad-atlas"
	"git.d-ma.be/mathias/cad-atlas/internal/atlas"
	"git.d-ma.be/mathias/cad-atlas/internal/cluster"
	"git.d-ma.be/mathias/cad-atlas/internal/gitea"
	"git.d-ma.be/mathias/cad-atlas/internal/version"

	"git.d-ma.be/mathias/cad/adapters/gitearead"
	cadapp "git.d-ma.be/mathias/cad/app"
	caddomain "git.d-ma.be/mathias/cad/domain"
)

// atlasHTML is the Phase-A/B static shell. It fetches /api/atlas.json at load
// and renders from that data (no inline arrays), so the content is sourced.
//
//go:embed static/cad-atlas.html
var atlasHTML []byte

// NewHandler serves the CAD Atlas: the shell at "/", and the sourced data at
// "/api/atlas.json" (authored data + CI stage generated from the real cd.yml +
// substrate overlaid from the live cluster when reachable).
func NewHandler() http.Handler {
	mux := http.NewServeMux()
	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/" {
			http.NotFound(w, r)
			return
		}
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		_, _ = w.Write(atlasHTML)
	})
	mux.HandleFunc("/api/atlas.json", func(w http.ResponseWriter, r *http.Request) {
		a, err := atlas.Default(cadatlas.CDWorkflow)
		if err != nil {
			http.Error(w, "atlas build failed", http.StatusInternalServerError)
			return
		}
		a.Version = version.Value
		ld := liveOverlay()
		if len(ld.hosts) > 0 {
			a.Substrate = atlas.MergeSubstrate(a.Substrate, ld.hosts)
		}
		if ld.ns != "" {
			a.NS = "Tailscale mesh · " + ld.ns
		}
		a.Timeline = ld.timeline
		if ld.run != nil {
			nodes := atlas.RunNodes(*ld.run)
			for i := range a.Stages {
				if a.Stages[i].Generate.Has("ci-jobs") {
					a.Stages[i].Nodes = nodes
				}
			}
			a.CIDurationS, a.CDDurationS = atlas.StageSeconds(*ld.run)
		}
		atlas.PrependGenerated(&a, "gitea-issues", ld.issues)
		atlas.PrependGenerated(&a, "gitea-repos", ld.repos)
		// cad-atlas#11: overlay mathias/cad#14's cad-stuck findings as
		// per-stage badges. Read-only — ApplyStuckOverlay only adds Nodes
		// with a link out; it never writes anything back to Gitea.
		a.Stages = atlas.ApplyStuckOverlay(a.Stages, ld.stuck)
		if ld.deploy != nil || ld.flux != nil {
			var live []atlas.Node
			if ld.deploy != nil {
				live = append(live, atlas.DeployNode(*ld.deploy))
			}
			if ld.flux != nil {
				live = append(live, atlas.FluxNode(*ld.flux))
			}
			for i := range a.Stages {
				if a.Stages[i].Generate.Has("deploy-state") {
					a.Stages[i].Nodes = append(live, a.Stages[i].Nodes...)
				}
			}
		}
		w.Header().Set("Content-Type", "application/json; charset=utf-8")
		_ = json.NewEncoder(w).Encode(a)
	})
	return mux
}

// liveOverlay holds cluster-sourced substrate facts (node specs + namespace line).
type liveOverlayData struct {
	hosts    []atlas.Host
	ns       string
	run      *atlas.RunSummary
	deploy   *atlas.Deploy
	flux     *atlas.Flux
	timeline []atlas.RunDot
	issues   []atlas.Node
	repos    []atlas.Node
	stuck    []caddomain.StuckFinding
}

// stuckRepos is the estate cad-stuck queries — mirrors mathias/dispatch's
// dispatch-repos.txt scope. Override with CAD_ATLAS_STUCK_REPOS (comma
// separated "owner/name" entries) so this doesn't need a redeploy every time
// the estate's repo list changes; cad-atlas has no filesystem access to the
// canonical dispatch-repos.txt at runtime.
var defaultStuckRepos = []string{
	"mathias/dispatch-sandbox", "mathias/cobalt-dingo", "mathias/parallax",
	"mathias/cad-atlas", "mathias/brain-gardener", "mathias/hyperguild", "mathias/brain",
}

func stuckRepos() []string {
	if v := os.Getenv("CAD_ATLAS_STUCK_REPOS"); v != "" {
		var repos []string
		for _, r := range strings.Split(v, ",") {
			if r = strings.TrimSpace(r); r != "" {
				repos = append(repos, r)
			}
		}
		return repos
	}
	return defaultStuckRepos
}

// live cache: query the cluster at most once per TTL; fall back to the authored
// substrate/ns (zero values) whenever the cluster is unreachable.
var (
	liveMu    sync.Mutex
	liveCache liveOverlayData
	liveAt    time.Time
)

const liveTTL = 30 * time.Second

func liveOverlay() liveOverlayData {
	liveMu.Lock()
	defer liveMu.Unlock()
	if !liveAt.IsZero() && time.Since(liveAt) < liveTTL {
		return liveCache
	}
	liveAt = time.Now()

	var d liveOverlayData
	if raw, err := cluster.Nodes(); err == nil {
		if hosts, err := atlas.HostsFromNodes(raw); err == nil {
			d.hosts = hosts
		}
	}
	if raw, err := cluster.Namespaces(); err == nil {
		if s, err := atlas.NamespaceSummary(raw); err == nil {
			d.ns = s
		}
	}
	if raw, err := gitea.Runs(); err == nil {
		if r, err := atlas.LatestRunJobs(raw); err == nil {
			d.run = &r
		}
		if dots, err := atlas.RecentRuns(raw, 12); err == nil {
			d.timeline = dots
		}
	}
	if raw, err := gitea.MyIssues(); err == nil {
		if nodes, err := atlas.IssueNodes(raw); err == nil {
			d.issues = nodes
		}
	}
	if raw, err := gitea.MyRepos(); err == nil {
		if nodes, err := atlas.RepoNodes(raw); err == nil {
			d.repos = nodes
		}
	}
	if raw, err := cluster.Deployment(); err == nil {
		if dep, err := atlas.DeployState(raw); err == nil {
			d.deploy = &dep
		}
	}
	if raw, err := cluster.FluxKustomization(); err == nil {
		if f, err := atlas.FluxStatus(raw); err == nil {
			d.flux = &f
		}
	}
	d.stuck = fetchStuck()
	liveCache = d
	return d
}

// fetchStuck re-derives cad#14's stuck worklist fresh on every liveOverlay
// call (no cache beyond the shared liveTTL) — the same "re-derive, never
// recall" discipline cad-stuck and cad-babysit both hold to. Read-only:
// gitearead.Client has no write method in its package. Degrades to nil
// (no badges rendered) on any error or when GITEA_TOKEN is unset, exactly
// like every other liveOverlay source — a forge outage costs a missing
// overlay, never a broken page.
func fetchStuck() []caddomain.StuckFinding {
	token := os.Getenv("GITEA_TOKEN")
	if token == "" {
		return nil
	}
	base := os.Getenv("GITEA_BASE")
	if base == "" || strings.Contains(base, ".svc.cluster.local") {
		// The in-cluster Gitea service (internal/gitea's default) has no
		// public HTTPS endpoint for gitearead's client to call with a
		// bearer token in the same way; cad-stuck's own default (the public
		// git.d-ma.be) is the correct base here regardless of what
		// GITEA_BASE is set to for the read-only in-cluster fetchers above.
		base = "https://git.d-ma.be"
	}
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	client := gitearead.New(base, token)
	cfg := cadapp.DefaultStuckConfig()
	cfg.BaseURL = base
	findings, _, err := cadapp.RunStuckQuery(ctx, client, stuckRepos(), cfg)
	if err != nil {
		return nil
	}
	return findings
}