// matrixd is the matrix indexer service. Wraps internal/matrix's
// Retriever with HTTP routes per docs/SPEC.md §3.4.
//
// Routes:
//   POST /matrix/search             — multi-corpus retrieve+merge,
//                                      with optional playbook boost
//   GET  /matrix/corpora            — list known vectord indexes
//   POST /matrix/relevance          — adjacency-pollution filter
//   POST /matrix/downgrade          — strong-model downgrade gate
//   POST /matrix/playbooks/record   — record a single (query → answer)
//                                      success for the learning loop
//   POST /matrix/playbooks/bulk     — bulk-record N successes; useful
//                                      for backfilling historical
//                                      placement data into the
//                                      playbook substrate
//
// matrixd talks to embedd (for query-text embedding) and vectord
// (for per-corpus search) via HTTP. Both URLs come from
// [matrixd] config; gateway sets them to its own upstream URLs so
// matrixd inherits the same provider topology.
package main

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

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

	"git.agentview.dev/profit/golangLAKEHOUSE/internal/matrix"
	"git.agentview.dev/profit/golangLAKEHOUSE/internal/shared"
)

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)
	}
	if cfg.Matrixd.EmbeddURL == "" || cfg.Matrixd.VectordURL == "" {
		slog.Error("matrixd: embedd_url and vectord_url required in [matrixd]")
		os.Exit(1)
	}

	retriever := matrix.New(cfg.Matrixd.EmbeddURL, cfg.Matrixd.VectordURL)
	h := &handlers{r: retriever, weakModels: cfg.Models.WeakModels}

	if err := shared.Run("matrixd", cfg.Matrixd.Bind, h.register, cfg.Auth); err != nil {
		slog.Error("server", "err", err)
		os.Exit(1)
	}
}

type handlers struct {
	r *matrix.Retriever
	// weakModels comes from cfg.Models.WeakModels at startup. Threaded
	// into every DowngradeInput so the gate uses the configured list
	// instead of matrix.DefaultWeakModels. nil/empty falls back to
	// the package default — matches pre-Phase 2 behavior.
	weakModels []string
}

func (h *handlers) register(r chi.Router) {
	r.Post("/matrix/search", h.handleSearch)
	r.Get("/matrix/corpora", h.handleCorpora)
	r.Post("/matrix/relevance", h.handleRelevance)
	r.Post("/matrix/downgrade", h.handleDowngrade)
	r.Post("/matrix/playbooks/record", h.handlePlaybookRecord)
	r.Post("/matrix/playbooks/bulk", h.handlePlaybookBulk)
}

func (h *handlers) handleSearch(w http.ResponseWriter, r *http.Request) {
	var req matrix.SearchRequest
	if !decodeJSON(w, r, &req) {
		return
	}
	resp, err := h.r.Search(r.Context(), req)
	if err != nil {
		writeMatrixError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, resp)
}

// relevanceRequest is the POST /matrix/relevance body. Threshold
// defaults to matrix.DefaultRelevanceThreshold when zero.
type relevanceRequest struct {
	Focus     matrix.FocusFile        `json:"focus"`
	Chunks    []matrix.CandidateChunk `json:"chunks"`
	Threshold float64                 `json:"threshold,omitempty"`
}

func (h *handlers) handleRelevance(w http.ResponseWriter, r *http.Request) {
	var req relevanceRequest
	if !decodeJSON(w, r, &req) {
		return
	}
	if len(req.Chunks) == 0 {
		http.Error(w, "chunks must be non-empty", http.StatusBadRequest)
		return
	}
	threshold := req.Threshold
	if threshold == 0 {
		threshold = matrix.DefaultRelevanceThreshold
	}
	res := matrix.FilterChunks(req.Focus, req.Chunks, threshold)
	writeJSON(w, http.StatusOK, res)
}

// playbookRecordRequest is the POST /matrix/playbooks/record body.
// Corpus is optional; defaults to matrix.DefaultPlaybookCorpus.
// Role is optional; when set, gates Shape A boost + Shape B inject
// at retrieve time so this entry only fires for queries with the
// same role (real_001 cross-role bleed fix). Empty Role = current
// behavior (no gate).
type playbookRecordRequest struct {
	QueryText    string   `json:"query_text"`
	Role         string   `json:"role,omitempty"`
	AnswerID     string   `json:"answer_id"`
	AnswerCorpus string   `json:"answer_corpus"`
	Score        float64  `json:"score"`
	Tags         []string `json:"tags,omitempty"`
	Corpus       string   `json:"corpus,omitempty"`
}

func (h *handlers) handlePlaybookRecord(w http.ResponseWriter, r *http.Request) {
	var req playbookRecordRequest
	if !decodeJSON(w, r, &req) {
		return
	}
	entry := matrix.NewPlaybookEntryWithRole(req.QueryText, req.Role, req.AnswerID, req.AnswerCorpus, req.Score, req.Tags)
	if err := entry.Validate(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	pbID, err := h.r.Record(r.Context(), entry, req.Corpus)
	if err != nil {
		slog.Warn("playbook record", "err", err)
		http.Error(w, err.Error(), http.StatusBadGateway)
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{
		"playbook_id":   pbID,
		"query_text":    entry.QueryText,
		"answer_id":     entry.AnswerID,
		"answer_corpus": entry.AnswerCorpus,
		"score":         entry.Score,
	})
}

// playbookBulkRequest is the POST /matrix/playbooks/bulk body —
// component C (operational rating wiring). Used to backfill
// historical placement data, or batch-record a session's worth of
// coordinator click-tracking. Each Entry is recorded independently;
// failures are reported per-entry without aborting the batch.
type playbookBulkRequest struct {
	Entries []playbookRecordRequest `json:"entries"`
	Corpus  string                  `json:"corpus,omitempty"` // applies to all if entry-level not set
}

// playbookBulkResult reports per-entry outcomes plus the aggregate
// count. Errors include the entry index so callers can locate the
// offending record without diffing.
type playbookBulkResult struct {
	Recorded int                      `json:"recorded"`
	Failed   int                      `json:"failed"`
	Results  []playbookBulkItemResult `json:"results"`
}

type playbookBulkItemResult struct {
	Index      int    `json:"index"`
	PlaybookID string `json:"playbook_id,omitempty"`
	Error      string `json:"error,omitempty"`
}

func (h *handlers) handlePlaybookBulk(w http.ResponseWriter, r *http.Request) {
	var req playbookBulkRequest
	if !decodeJSON(w, r, &req) {
		return
	}
	if len(req.Entries) == 0 {
		http.Error(w, "entries must be non-empty", http.StatusBadRequest)
		return
	}

	out := playbookBulkResult{
		Results: make([]playbookBulkItemResult, len(req.Entries)),
	}
	for i, item := range req.Entries {
		corpus := item.Corpus
		if corpus == "" {
			corpus = req.Corpus
		}
		entry := matrix.NewPlaybookEntryWithRole(item.QueryText, item.Role, item.AnswerID, item.AnswerCorpus, item.Score, item.Tags)
		if err := entry.Validate(); err != nil {
			out.Results[i] = playbookBulkItemResult{Index: i, Error: err.Error()}
			out.Failed++
			continue
		}
		pbID, err := h.r.Record(r.Context(), entry, corpus)
		if err != nil {
			out.Results[i] = playbookBulkItemResult{Index: i, Error: err.Error()}
			out.Failed++
			continue
		}
		out.Results[i] = playbookBulkItemResult{Index: i, PlaybookID: pbID}
		out.Recorded++
	}
	writeJSON(w, http.StatusOK, out)
}

// downgradeRequest is the POST /matrix/downgrade body. Mirrors
// matrix.DowngradeInput. When ForceFullOverride is omitted from
// the body, the value falls back to matrixd's process env
// (LH_FORCE_FULL_ENRICHMENT) — an opinionated default that lets
// operators set the env var on the matrixd unit and have every
// gate decision honor it without per-request changes. Per
// 2026-04-29 cross-lineage scrum (Opus WARN): callers that want
// deterministic gate behavior independent of matrixd's env should
// pass ForceFullOverride explicitly in the body.
type downgradeRequest struct {
	Mode              string `json:"mode"`
	Model             string `json:"model"`
	ForcedMode        bool   `json:"forced_mode,omitempty"`
	ForceFullOverride *bool  `json:"force_full_override,omitempty"`
}

func (h *handlers) handleDowngrade(w http.ResponseWriter, r *http.Request) {
	var req downgradeRequest
	if !decodeJSON(w, r, &req) {
		return
	}
	if req.Mode == "" || req.Model == "" {
		http.Error(w, "mode and model are required", http.StatusBadRequest)
		return
	}
	in := matrix.NewDowngradeInputFromEnv(req.Mode, req.Model, req.ForcedMode)
	if req.ForceFullOverride != nil {
		// Explicit body override beats env, useful for tooling that
		// wants to ask "what would the gate do under these conditions"
		// without env pollution.
		in.ForceFullOverride = *req.ForceFullOverride
	}
	in.WeakModels = h.weakModels
	writeJSON(w, http.StatusOK, matrix.MaybeDowngrade(in))
}

func (h *handlers) handleCorpora(w http.ResponseWriter, r *http.Request) {
	names, err := h.r.Corpora(r.Context())
	if err != nil {
		slog.Error("matrix corpora", "err", err)
		http.Error(w, "vectord unavailable", http.StatusBadGateway)
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"corpora": names, "count": len(names)})
}

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("matrix write json", "err", err)
	}
}

// writeMatrixError maps internal/matrix sentinels to HTTP statuses.
// Corpus / embed failures bubble up as 502 (the upstream service is
// what's wrong); validation errors are 400.
func writeMatrixError(w http.ResponseWriter, err error) {
	switch {
	case errors.Is(err, matrix.ErrEmptyCorpora),
		errors.Is(err, matrix.ErrEmptyQuery):
		http.Error(w, err.Error(), http.StatusBadRequest)
	case errors.Is(err, matrix.ErrCorpus),
		errors.Is(err, matrix.ErrEmbed):
		slog.Warn("matrix upstream", "err", err)
		http.Error(w, err.Error(), http.StatusBadGateway)
	default:
		slog.Error("matrix", "err", err)
		http.Error(w, "internal", http.StatusInternalServerError)
	}
}
