package pipeline

import (
	"encoding/json"
	"strings"

	"textmachine/backend/internal/checks"
)

// quality.go: the DETERMINISTIC per-run quality-report (D39 layer 5, H5-no-in-loop-quality-signal) —
// the online/offline quality telemetry the owner asked for "from day one" (п.25/п.31), which
// research/18 §C1 #10 flagged as a NOW lever but was silently deferred to Ф2. It AGGREGATES signals
// that are ALREADY computed and stored (retrieval_state: glossary post-check misses, cheap style
// flaggers, trust-gated suppressions; chunk_status: echo/CJK/sanitizer flags) plus ONE cheap
// deterministic structural KPI (sentences per narrative paragraph — the "choppy paragraphs" claim-1
// signal) recomputed from the exported final text. It is a PURE READ-ONLY projection like Status: $0,
// no LLM, no snapshot touch, no checkpoint replay — only OBSERVABILITY, never a gate. The semantic
// span-judge (inversion/omission backstop for claim-2) is NOT here — it is research-dependent (pack-2).

// QualityReport is the whole-book per-run quality projection. The shipping granularity is the OUTPUT UNIT
// (edit unit for an edit pipeline, draft chunk for a draft-only one), so the whole-book counters are named
// *_units (naming-debt fix D39.18-follow-up: pre-c-lite they said "chunks" but count units).
type QualityReport struct {
	BookID     string `json:"book_id"`
	TotalUnits int    `json:"total_units"`
	// TextUnits is the number of units whose exported final text was available for the structural KPI
	// (done or cosmetically-stripped); a flagged-empty unit contributes no prose.
	TextUnits int `json:"text_units"`
	// ProcessedUnits is the number of units that REACHED the final stage (a final-stage row exists: ok,
	// cosmetic-strip, or skipped-because-a-member-flagged) — the strip-rate denominator, so the rate is a
	// bounded [0,1] fraction of processed units.
	ProcessedUnits int `json:"processed_units"`

	// Claim-1 structural KPI (choppy paragraphs). MeanSentPerNarrPara ≈ 1 is choppy (one sentence per
	// paragraph — the owner's exact complaint); higher is merged discourse prose. Aggregated as
	// total sentences / total narrative paragraphs across the book, so it is a true book-wide mean.
	NarrativeSentences  int     `json:"narrative_sentences"`
	NarrativeParagraphs int     `json:"narrative_paragraphs"`
	MeanSentPerNarrPara float64 `json:"mean_sentences_per_narrative_paragraph"`

	// Deterministic signal aggregates (all observability, never a disposition).
	DialogueDashFlags  int `json:"dialogue_dash_flags"`  // Rosenthal dialogue-dash inconsistencies
	GlossaryMisses     int `json:"glossary_misses"`      // CONFIRMED post-check misses (D10 consistency)
	NumberDriftFlags   int `json:"number_drift_flags"`   // reflow number drift + 万/億 magnitude drift
	TrustGated         int `json:"trust_gated"`          // lower-trust suppressions refused (seed hygiene)
	CosmeticStripUnits int `json:"cosmetic_strip_units"` // units the sanitizer auto-stripped (markdown header OR CJK leak — F6)

	// Echo is SPLIT by stage (owner decision, D39.18-follow-up): a translator echo (draft) and an editor
	// echo (edit) measure different things and were conflated by the old single echo_rate + a c-lite
	// re-derive hack. echo_draft = the DRAFT quality (fraction of draft-stage rows flagged cjk_artifact,
	// INCLUDING a c-lite dropped member — the translator echoed even if the editor recovered the unit),
	// computed DIRECTLY from the draft rows (no per-unit re-derivation). echo_edit = the DELIVERED quality
	// (fraction of edit-stage units whose EDITOR output itself echoed — a skipped edit row is a draft echo,
	// not an editor one, so it is excluded from the numerator).
	EchoDraftChunks int     `json:"echo_draft_chunks"` // draft-stage rows flagged cjk_artifact (per DRAFT chunk)
	EchoDraftRate   float64 `json:"echo_draft_rate"`   // over live draft rows
	EchoEditUnits   int     `json:"echo_edit_units"`   // edit-stage units whose editor output echoed
	EchoEditRate    float64 `json:"echo_edit_rate"`    // over live edit rows

	// CosmeticStripRate is over ProcessedUnits (0..1). It covers BOTH strip classes (a markdown-only strip
	// is NOT a CJK leak — F6, D39.4: the old cjk_leak_rate counted every sanitizer_stripped unit).
	CosmeticStripRate float64 `json:"cosmetic_strip_rate"`

	// RepairCandidates is the ADDRESSABLE-defect residual (pack-16, D39.24): how many defects of the
	// anchored classes survive in the SHIPPED text of this run, counted after the uniqueness and
	// disjointness guards — i.e. how many a repair loop would actually attack. It is the measurement that
	// gates whether the paid loop is worth enabling at all, and it costs $0: the same read-only projection
	// that already recomputes the structural KPI re-runs the deterministic detectors over the exported text
	// and the manifest source. Zero for a book whose pair/target ships no checker data.
	//
	// CAVEAT (stated, not silent): the scan measures the EXPORT-normalised text, while the in-loop detector
	// would see the raw completion. The two differ only by the recoverable-glyph fold, so a candidate count
	// can differ by the rare defect that the export contract itself repairs.
	RepairCandidates int `json:"repair_candidates,omitempty"`
	// RepairCandidatesByClass breaks the residual down per class (json.Marshal sorts the keys, so the
	// rendering is deterministic). nil when nothing fired, so a clean book's report is byte-identical to
	// what it was before this field existed.
	RepairCandidatesByClass map[string]int `json:"repair_candidates_by_class,omitempty"`
	// RepairCalls / RepairApplied / RepairDeclined / RepairRejected are the loop's OUTCOME counters, DERIVED
	// from durable artifacts rather than stored (§15.2 B): a counter column on retrieval_state would be wiped
	// by the draft wave's unconditional row rewrite on every resumed run, while checkpoints and the derived
	// final_hash namespace survive. Declined = the model answered "no change", i.e. OUR flag was the false
	// positive — the loop's own precision measurement. All omitempty: a book that never repaired is
	// byte-identical to before these fields existed.
	RepairCalls    int `json:"repair_calls,omitempty"`
	RepairApplied  int `json:"repair_applied,omitempty"`
	RepairDeclined int `json:"repair_declined,omitempty"`
	RepairRejected int `json:"repair_rejected,omitempty"`

	// DegenerateLoopRuns counts runs of ≥ segmentLoopMinRun consecutive units whose exported MODEL text is
	// byte-identical after whitespace normalization — a degenerate translation loop (pack-13 point-10,
	// research/21; complements echoMineViolation on the degenerate path research/15). Observability only,
	// never a disposition or a wire touch; 0 on a healthy book (every unit's source, and so its translation,
	// differs). The signature is over the MODEL output (checks.ExportNormalize, BEFORE the deterministic title is
	// prepended), so a per-chapter «Глава N» never masks a body loop. omitempty keeps a loop-free run's
	// report byte-identical to before this field existed.
	DegenerateLoopRuns int `json:"degenerate_loop_runs,omitempty"`

	Chunks []ChunkQuality `json:"chunks,omitempty"`
}

// ChunkQuality is one chunk's per-chunk quality row (the "where did quality slip" signal).
type ChunkQuality struct {
	Chapter             int `json:"chapter"`
	ChunkIdx            int `json:"chunk_idx"`
	NarrativeSentences  int `json:"narrative_sentences"`
	NarrativeParagraphs int `json:"narrative_paragraphs"`
	DialogueDashFlags   int `json:"dialogue_dash_flags"`
	GlossaryMisses      int `json:"glossary_misses"`
	NumberDriftFlags    int `json:"number_drift_flags"`
	TrustGated          int `json:"trust_gated"`
	// RepairCandidates is this unit's addressable-defect residual (pack-16); omitted when zero so a clean
	// unit's row is byte-identical to what it was before the field existed.
	RepairCandidates int `json:"repair_candidates,omitempty"`
}

// QualityReport builds the read-only per-run quality projection. It opens no jobs, reserves nothing,
// makes no LLM call — it reads the persisted chunk_status / retrieval_state and, for each chunk with
// an exported final text, the $0 final checkpoint to recompute the structural KPI. Safe to run
// whenever `report`/`status` are (the same exclusive-lock rule). Deterministic over the store.
// CAVEAT (same class as Status's config-drift): the exported-text signals key on the CURRENT config's
// final-stage NAME; if a config edit renamed the final stage since the run, the stored rows use the
// old name and the structural KPI / echo / CJK rates read 0 (the underlying spend/verdict rows are
// untouched — surface `status` shows the drift). A run under the same config reads correctly.
func (r *Runner) QualityReport() (*QualityReport, error) {
	statuses, err := r.Store.ChunkStatusesForBook(r.Book.BookID)
	if err != nil {
		return nil, err
	}
	states, err := r.Store.RetrievalStatesForBook(r.Book.BookID)
	if err != nil {
		return nil, err
	}
	// Total = the SHIPPING units (the manifest re-chunk, $0), matching status/export + the per-unit
	// BookResult (R1): under the wave model the editor's final text is per EDIT UNIT, so ProcessedUnits
	// (the lastStage rows, one per unit leader) and TotalUnits agree at unit granularity. The per-unit
	// KPI/strip signals land on the leader's edit row; a non-leader member's ChunkQuality row carries
	// only its draft-side signals (trust-gated) with a 0 structural KPI — observability, never a gate.
	chunks, err := r.bookChunks()
	if err != nil {
		return nil, err
	}
	units := r.outputUnits(chunks)
	// GHOST guard (parity with Export/Status): a stored row whose unit-leader key is NOT in the current
	// manifest (source shrank since the run) is a ghost — dropping it keeps ProcessedUnits ≤ TotalUnits.
	inManifest := map[chunkKey]bool{}
	for _, u := range units {
		inManifest[chunkKey{u.Chapter, u.FirstChunkIdx}] = true
	}
	// A retrieval_state row / a draft echo is keyed per DRAFT chunk, so it is live iff its chunk is still in
	// the manifest; a chunk that left the source is a ghost.
	liveChunks := map[chunkKey]bool{}
	for _, ch := range chunks {
		liveChunks[chunkKey{ch.Chapter, ch.ChunkIdx}] = true
	}
	// Unit source, keyed by the leader row the final-stage verdict lives on — the src side the comparative
	// detectors need. It is the $0 manifest re-chunk (never a stored or billed artifact), joined exactly as
	// the editor's input is (wave.go sourceText).
	unitSource := make(map[chunkKey]string, len(units))
	for _, u := range units {
		unitSource[chunkKey{u.Chapter, u.FirstChunkIdx}] = u.sourceText()
	}
	repairCfg := r.cheapGateConfig()
	// Same target gate the in-loop path applies: the Latin-residue class cannot be made inert by data, so on
	// a Latin-script target it would report every word as an addressable defect and make the residual
	// meaningless. A target without the readability gate simply reports the data-driven classes.
	repairLatinOK := isRuTarget(r.Book.TargetLang)
	// Wave stage-name sets classify a stored chunk_status row by wave for the split echo metric (D39.18
	// owner decision): echo_draft is counted DIRECTLY from the draft rows (no c-lite per-unit re-derivation
	// — a dropped member's own draft row already carries cjk_artifact), echo_edit from the edit rows.
	draftStageNames := stageNameSet(r.waveStagesIndexed(waveDraft))
	editStageNames := stageNameSet(r.waveStagesIndexed(waveEdit))

	rep := &QualityReport{BookID: r.Book.BookID, TotalUnits: len(units)}
	byChunk := map[chunkKey]*ChunkQuality{}
	order := []chunkKey{}
	chunkOf := func(k chunkKey) *ChunkQuality {
		if q := byChunk[k]; q != nil {
			return q
		}
		q := &ChunkQuality{Chapter: k.chapter, ChunkIdx: k.chunkIdx}
		byChunk[k] = q
		order = append(order, k)
		return q
	}

	// The glossary post-check GATE flips a chunk to withheld (flagged glossary_miss, empty export) at
	// the CHUNK level without a chunk_status row (like Export/Status re-derive it). F5 (D39.4): the
	// structural KPI must EXCLUDE these — their export is "", so counting their (withheld) text in
	// TextUnits/KPI diverges from what `tmctl export` and `translate` actually ship.
	gateOn := r.Pipeline.Gates.Glossary.PostcheckGate
	withheld := map[chunkKey]bool{}

	// Aggregate the stored retrieval-state signals (glossary consistency, style breakdown, trust-gated).
	// A retrieval_state row is keyed per DRAFT chunk (live iff its chunk is still in the manifest); a leader
	// row also carries the unit's post-check, so if the leader survives, so does the unit.
	for _, rs := range states {
		if !liveChunks[chunkKey{rs.Chapter, rs.ChunkIdx}] {
			continue // ghost retrieval_state row (chunk dropped from source)
		}
		q := chunkOf(chunkKey{rs.Chapter, rs.ChunkIdx})
		q.GlossaryMisses += rs.NPostcheckMiss
		q.TrustGated += rs.NTrustGatedSuppress
		rep.GlossaryMisses += rs.NPostcheckMiss
		rep.TrustGated += rs.NTrustGatedSuppress
		if gateOn && rs.NPostcheckMiss > 0 {
			withheld[chunkKey{rs.Chapter, rs.ChunkIdx}] = true
		}
		if rs.NStyleFlags > 0 && rs.StyleDetail != "" {
			var cg checks.CheapGateResult
			if json.Unmarshal([]byte(rs.StyleDetail), &cg) == nil {
				dash := cg.DialogueDash
				drift := cg.NumberDrift + cg.NumberMagnitude
				q.DialogueDashFlags += dash
				q.NumberDriftFlags += drift
				rep.DialogueDashFlags += dash
				rep.NumberDriftFlags += drift
			}
		}
	}

	// Split echo by stage (D39.18 owner decision): echo_draft over the DRAFT-stage rows (translator quality,
	// INCLUDING a c-lite dropped member — its own draft row carries cjk_artifact, so no per-unit re-derivation
	// is needed), echo_edit over the EDIT-stage rows (delivered quality — only the EDITOR's own echo counts,
	// a skipped edit row is a draft echo not an editor one). Ghost-guarded like the rest (live chunks / units).
	var draftRows, draftEcho, editRows, editEcho int
	for _, cs := range statuses {
		k := chunkKey{cs.Chapter, cs.ChunkIdx}
		switch {
		case draftStageNames[cs.Stage] && liveChunks[k]:
			draftRows++
			if cs.FlagReason == string(FlagCJKArtifact) {
				draftEcho++ // the translator echoed CJK (a flagged draft row), incl. a c-lite dropped member
			}
		case editStageNames[cs.Stage] && inManifest[k]:
			editRows++
			if cs.Disposition == string(DispFlagged) && cs.FlagReason == string(FlagCJKArtifact) {
				editEcho++ // the EDITOR's OWN output echoed (a skipped edit row means the drafts echoed, not the editor)
			}
		}
	}
	rep.EchoDraftChunks, rep.EchoEditUnits = draftEcho, editEcho
	if draftRows > 0 {
		rep.EchoDraftRate = float64(draftEcho) / float64(draftRows)
	}
	if editRows > 0 {
		rep.EchoEditRate = float64(editEcho) / float64(editRows)
	}

	// The exported-text units (the FINAL stage's row): the cosmetic-strip rate + the structural KPI.
	lastStage := ""
	if n := len(r.Pipeline.Stages); n > 0 {
		lastStage = r.Pipeline.Stages[n-1].Name
	}
	loopText := map[chunkKey]string{} // per-unit exported MODEL text (no title), for the pack-13 point-10 loop scan
	for _, cs := range statuses {
		k := chunkKey{cs.Chapter, cs.ChunkIdx}
		if cs.Stage != lastStage || !inManifest[k] {
			continue // the final verdict lives on the final stage's row (per unit); drop ghost leader rows
		}
		// Every unit that REACHED the final stage has exactly one lastStage row (ok, cosmetic-strip, or
		// skipped-because-a-member-flagged) — the strip-rate denominator.
		rep.ProcessedUnits++
		if cs.FlagReason == string(FlagSanitizerStripped) {
			rep.CosmeticStripUnits++ // a stripped unit carried a markdown OR CJK cosmetic leak (F6)
		}
		// Structural KPI: recompute over the exported final text (ok, or the cosmetic-stripped export).
		if cs.FinalHash == "" {
			continue
		}
		if cs.Disposition != string(DispOK) && cs.FlagReason != string(FlagSanitizerStripped) {
			continue // a dropped unit exported nothing
		}
		if withheld[k] {
			continue // F5: the glossary gate withheld this unit's text — it exports nothing
		}
		cp, cperr := r.Store.GetCheckpoint(cs.FinalHash)
		if cperr != nil {
			return nil, cperr
		}
		if cp == nil || strings.TrimSpace(cp.ResponseText) == "" {
			continue
		}
		normText := checks.ExportNormalize(cp.ResponseText)
		loopText[k] = normText
		// Addressable-defect residual (pack-16): the same guards the repair sub-step applies — uniqueness
		// inside RepairCandidates, then sentence-expansion + disjointness — so the number is «how many
		// repairs would actually be attempted», not «how many flags exist».
		scanned := checks.RepairCandidates(unitSource[k], normText, repairCfg)
		if !repairLatinOK {
			kept := scanned[:0]
			for _, c := range scanned {
				if c.Class != checks.RepairLatinResidue {
					kept = append(kept, c)
				}
			}
			scanned = kept
		}
		if cands := checks.DisjointCandidates(normText, scanned); len(cands) > 0 {
			if rep.RepairCandidatesByClass == nil {
				rep.RepairCandidatesByClass = map[string]int{}
			}
			for _, c := range cands {
				rep.RepairCandidatesByClass[string(c.Class)]++
			}
			rep.RepairCandidates += len(cands)
			chunkOf(k).RepairCandidates += len(cands)
		}
		sent, para := checks.NarrativeStructure(normText)
		q := chunkOf(k)
		q.NarrativeSentences, q.NarrativeParagraphs = sent, para
		rep.NarrativeSentences += sent
		rep.NarrativeParagraphs += para
		rep.TextUnits++
	}

	// Degenerate-loop guard (pack-13 point-10): scan the exported MODEL texts in reading (manifest/unit)
	// order for runs of identical consecutive units — observability, never a gate. Deterministic.
	ordered := make([]string, 0, len(units))
	for _, u := range units {
		ordered = append(ordered, loopText[chunkKey{u.Chapter, u.FirstChunkIdx}])
	}
	rep.DegenerateLoopRuns = len(segmentLoopRuns(ordered, segmentLoopMinRun))

	// Repair outcomes, derived (never stored) — see the field docs.
	if calls, declined, applied, rerr := r.Store.RepairStats(r.Book.BookID, repairNoChange, repairDerivedNS+":"); rerr == nil {
		rep.RepairCalls, rep.RepairDeclined, rep.RepairApplied = calls, declined, applied
		if n := calls - declined - applied; n > 0 {
			rep.RepairRejected = n // paid, neither declined nor applied ⇒ a guard or the re-gate refused it
		}
	} else {
		return nil, rerr
	}
	if rep.NarrativeParagraphs > 0 {
		rep.MeanSentPerNarrPara = float64(rep.NarrativeSentences) / float64(rep.NarrativeParagraphs)
	}
	if rep.ProcessedUnits > 0 {
		rep.CosmeticStripRate = float64(rep.CosmeticStripUnits) / float64(rep.ProcessedUnits)
	}
	for _, k := range order {
		rep.Chunks = append(rep.Chunks, *byChunk[k])
	}
	return rep, nil
}