// observerd is the autonomous-iteration witness service. Port of
// the load-bearing pieces of mcp-server/observer.ts (Rust system).
//
// Routes (all under /observer):
//   GET  /observer/health        — service liveness + ring size
//   GET  /observer/stats         — aggregate counters + recent scenarios
//   POST /observer/event         — record one observed op
//
// Deferred to follow-up commits (see internal/observer doc):
//   - POST /observer/review (cloud-LLM hand review fall-back)
//   - background loops (analyzeErrors, consolidatePlaybooks,
//     tailOverseerCorrections)
//   - failure-cluster escalation to LLM Team
//
// /relevance was already ported to internal/matrix in 9588bd8 and is
// not duplicated here.

package main

import (
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"strings"
	"time"

	"github.com/go-chi/chi/v5"

	"git.agentview.dev/profit/golangLAKEHOUSE/internal/observer"
	"git.agentview.dev/profit/golangLAKEHOUSE/internal/shared"
	"git.agentview.dev/profit/golangLAKEHOUSE/internal/workflow"
)

const maxRequestBytes = 4 << 20 // 4 MiB cap on request bodies

func main() {
	configPath := flag.String("config", "lakehouse.toml", "path to TOML config")
	flag.Parse()

	cfg, err := shared.LoadConfig(*configPath)
	if err != nil {
		slog.Error("config", "err", err)
		os.Exit(1)
	}

	// Persistence is optional — empty path = ephemeral (matches the
	// pathwayd pattern). Production sets a stable path under
	// /var/lib/lakehouse/observer/ops.jsonl.
	var persistor *observer.Persistor
	if cfg.Observerd.PersistPath != "" {
		persistor, err = observer.NewPersistor(cfg.Observerd.PersistPath)
		if err != nil {
			slog.Error("observer persistor", "err", err)
			os.Exit(1)
		}
	}

	store := observer.NewStore(persistor)
	if persistor != nil {
		n, err := store.Load()
		if err != nil {
			slog.Warn("observer load", "err", err, "loaded", n)
		} else {
			slog.Info("observer loaded", "ops", n, "path", cfg.Observerd.PersistPath)
		}
	}

	runner := workflow.NewRunner()
	// matrixd URL: prefer explicit observerd config field, fall back
	// to gateway's matrixd_url so a single-toml deploy works without
	// duplicating the address.
	matrixdURL := cfg.Gateway.MatrixdURL
	registerBuiltinModes(runner, matrixdURL, cfg.Models.WeakModels)

	h := &handlers{store: store, runner: runner}
	if err := shared.Run("observerd", cfg.Observerd.Bind, h.register, cfg.Auth); err != nil {
		slog.Error("server", "err", err)
		os.Exit(1)
	}
}

type handlers struct {
	store  *observer.Store
	runner *workflow.Runner
}

func (h *handlers) register(r chi.Router) {
	r.Get("/observer/stats", h.handleStats)
	r.Post("/observer/event", h.handleEvent)
	r.Post("/observer/workflow/run", h.handleWorkflowRun)
	r.Get("/observer/workflow/modes", h.handleWorkflowModes)
}

func (h *handlers) handleStats(w http.ResponseWriter, _ *http.Request) {
	writeJSON(w, http.StatusOK, h.store.Stats())
}

func (h *handlers) handleEvent(w http.ResponseWriter, r *http.Request) {
	var op observer.ObservedOp
	if !decodeJSON(w, r, &op) {
		return
	}
	if err := h.store.Record(op); err != nil {
		if errors.Is(err, observer.ErrInvalidOp) {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}
		slog.Error("observer record", "err", err)
		http.Error(w, "internal", http.StatusInternalServerError)
		return
	}
	stats := h.store.Stats()
	writeJSON(w, http.StatusOK, map[string]any{
		"accepted":  true,
		"ring_size": stats.Total,
	})
}

// workflowRunRequest is the POST /observer/workflow/run body — a
// Workflow definition in JSON form (matches Archon's YAML shape but
// JSON-serialized for the HTTP path).
type workflowRunRequest struct {
	Workflow workflow.Workflow `json:"workflow"`
}

func (h *handlers) handleWorkflowRun(r http.ResponseWriter, req *http.Request) {
	var body workflowRunRequest
	if !decodeJSON(r, req, &body) {
		return
	}
	res, err := h.runner.Run(req.Context(), body.Workflow)
	// Record per-node provenance into the observer ring AS the
	// workflow runs — same shape as any other ObservedOp so the
	// existing /observer/stats aggregation surfaces workflow ops
	// alongside scenario ops without a schema change.
	for _, n := range res.Nodes {
		op := observer.ObservedOp{
			Endpoint:      "/observer/workflow/run/" + body.Workflow.Name + "/" + n.NodeID,
			InputSummary:  fmt.Sprintf("workflow=%s node=%s mode=%s", body.Workflow.Name, n.NodeID, n.Mode),
			Success:       n.Error == "",
			DurationMs:    n.DurationMs,
			OutputSummary: summarizeOutput(n.Output),
			Source:        observer.SourceWorkflow,
			Error:         n.Error,
			Timestamp:     n.StartedAt.UTC().Format(time.RFC3339Nano),
		}
		if recErr := h.store.Record(op); recErr != nil {
			slog.Warn("workflow run: provenance record failed", "err", recErr)
		}
	}
	if err != nil {
		// Aborting errors (cycle, missing dep, unknown mode) — surface
		// as 4xx because the workflow definition itself is wrong.
		slog.Warn("workflow run aborted", "err", err)
		writeJSON(r, http.StatusBadRequest, map[string]any{
			"error":  err.Error(),
			"result": res,
		})
		return
	}
	writeJSON(r, http.StatusOK, res)
}

func (h *handlers) handleWorkflowModes(w http.ResponseWriter, _ *http.Request) {
	modes := h.runner.Modes()
	writeJSON(w, http.StatusOK, map[string]any{
		"modes": modes,
		"count": len(modes),
	})
}

// summarizeOutput renders a workflow node's output map for the
// ObservedOp's OutputSummary string. Best-effort — long values get
// truncated rather than ballooning the ring buffer's memory.
func summarizeOutput(output map[string]any) string {
	if output == nil {
		return "(nil)"
	}
	bs, err := json.Marshal(output)
	if err != nil {
		return fmt.Sprintf("(marshal err: %v)", err)
	}
	if len(bs) > 256 {
		return string(bs[:256]) + "...(truncated)"
	}
	return string(bs)
}

// registerBuiltinModes wires the modes the runner knows about. The
// pure-function wrappers (matrix.relevance, matrix.downgrade,
// distillation.score, drift.scorer) are direct Go calls. matrix.search
// is HTTP-backed, pointed at the configured matrixd_url so workflows
// can compose retrieval into multi-pass measurement chains.
//
// Fixture modes (fixture.echo, fixture.upper) stay registered for
// the workflow_smoke that proves the runner mechanics independently
// of the real modes' availability.
//
// Real-mode follow-ups still pending:
//   - playbook.record (HTTP to matrixd)
//   - playbook.lookup (HTTP to matrixd)
//   - llm.chat (HTTP to gateway /v1/chat)
func registerBuiltinModes(r *workflow.Runner, matrixdURL string, weakModels []string) {
	// Fixture modes for runner mechanics smokes.
	r.RegisterMode("fixture.echo", func(_ workflow.Context, input map[string]any) (map[string]any, error) {
		out := make(map[string]any, len(input))
		for k, v := range input {
			out[k] = v
		}
		return out, nil
	})
	r.RegisterMode("fixture.upper", func(_ workflow.Context, input map[string]any) (map[string]any, error) {
		prompt, _ := input["prompt"].(string)
		return map[string]any{"upper": strings.ToUpper(prompt)}, nil
	})

	// Real modes — pure-function wrappers (no I/O).
	r.RegisterMode("matrix.relevance", workflow.MatrixRelevance)
	// matrix.downgrade reads weakModels from config — Phase 2.
	// nil/empty falls back to matrix.DefaultWeakModels per the
	// MatrixDowngradeWithWeakList factory contract.
	r.RegisterMode("matrix.downgrade", workflow.MatrixDowngradeWithWeakList(weakModels))
	r.RegisterMode("distillation.score", workflow.DistillationScore)
	r.RegisterMode("drift.scorer", workflow.DriftScorer)

	// HTTP-backed modes — only register when their backend URL is set.
	// matrixd_url defaults to a known address but tests/dev may run
	// without matrixd.
	if matrixdURL != "" {
		hc := &http.Client{Timeout: 30 * time.Second}
		r.RegisterMode("matrix.search", workflow.MatrixSearch(matrixdURL, hc))
	}
}

func decodeJSON(w http.ResponseWriter, r *http.Request, v any) bool {
	defer r.Body.Close()
	r.Body = http.MaxBytesReader(w, r.Body, maxRequestBytes)
	if err := json.NewDecoder(r.Body).Decode(v); err != nil {
		var maxErr *http.MaxBytesError
		if errors.As(err, &maxErr) || strings.Contains(err.Error(), "http: request body too large") {
			http.Error(w, "body too large", http.StatusRequestEntityTooLarge)
			return false
		}
		http.Error(w, "decode body: "+err.Error(), http.StatusBadRequest)
		return false
	}
	return true
}

func writeJSON(w http.ResponseWriter, code int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	if err := json.NewEncoder(w).Encode(v); err != nil {
		slog.Warn("observer write json", "err", err)
	}
}