import type {
  CandidateFieldMappingDecision,
  CandidateMappingResult
} from '../domain/candidate-mapping';
import type { ImportProfile } from '../domain/import-profile';
import type { ProfileFieldRule } from '../domain/tool-profile-definition';
import type { ImportRecognitionResult, RecognitionOverrides } from '../domain/import-recognition';
import type { FindingCandidate, SourceExtractionResult, SourceFieldCandidate } from '../domain/source-extraction';
import { recognitionConfidence } from '../recognition/confidence';
import { evaluateFieldRoleEvidence } from '../recognition/field-role-evidence';

interface CandidateFieldGroup {
  id: string;
  identity: string;
  fieldKey: string;
  sourceLabel: string;
  tableIndex?: number;
  values: string[];
  headers: string[];
}

function groupIdentity(field: SourceFieldCandidate): string {
  return JSON.stringify([field.source.tableIndex ?? null, field.key, field.label]);
}

function fieldGroups(candidates: FindingCandidate[], rules: ProfileFieldRule[]) {
  const groups = new Map<string, CandidateFieldGroup>();
  const contexts = new Map<FindingCandidate, string>();
  const conditions = rules.flatMap(rule => [...(rule.whenHeadersPresent ?? []), ...(rule.whenHeadersAbsent ?? [])]);
  candidates.forEach(candidate => {
    const headers = conditions.length ? candidate.fields.map(item => item.label) : [];
    const contextKey = conditions.map(pattern => headers.some(header => { pattern.lastIndex = 0; return pattern.test(header.trim()); }) ? '1' : '0').join('');
    contexts.set(candidate, contextKey);
    candidate.fields.forEach(field => {
      const identity = `${groupIdentity(field)}:${contextKey}`;
      const existing = groups.get(identity);
      if (existing) {
        if (existing.values.length < 250 && field.decodedValue.trim()) existing.values.push(field.decodedValue.trim());
        return;
      }
      groups.set(identity, {
        id: `candidate-field-${groups.size}`,
        identity,
        fieldKey: field.key,
        sourceLabel: field.label,
        tableIndex: field.source.tableIndex,
        headers,
        values: field.decodedValue.trim() ? [field.decodedValue.trim()] : []
      });
    });
  });
  return { groups: [...groups.values()], contexts };
}

function confirmedFieldDecision(
  recognition: ImportRecognitionResult | undefined,
  group: CandidateFieldGroup
) {
  if (group.tableIndex === undefined) return undefined;
  const columnIndex = Number(/^column-(\d+)$/.exec(group.fieldKey)?.[1]);
  if (!Number.isInteger(columnIndex)) return undefined;
  return recognition?.fields.find(field =>
    field.tableIndex === group.tableIndex
    && field.columnIndex === columnIndex
    && field.decisionSource === 'user-confirmed'
  );
}

function mapGroup(
  group: CandidateFieldGroup,
  profile: ImportProfile,
  recognition?: ImportRecognitionResult
): CandidateFieldMappingDecision {
  const confirmed = confirmedFieldDecision(recognition, group);
  if (confirmed) {
    return {
      id: group.id,
      fieldKey: group.fieldKey,
      sourceLabel: group.sourceLabel,
      sourceScope: { tableIndex: group.tableIndex },
      proposedRole: confirmed.proposedRole,
      appliedRole: confirmed.appliedRole,
      alternatives: confirmed.alternatives,
      confidence: confirmed.confidence,
      evidence: confirmed.evidence,
      decisionSource: 'user-confirmed',
      requiresConfirmation: false
    };
  }
  const alternatives = evaluateFieldRoleEvidence(group.sourceLabel, group.values, profile.definition.fieldRules, group.headers);
  const best = alternatives[0];
  const proposedRole = best && best.confidence.level !== 'unknown' ? best.role : null;
  const automaticallyApplied = best && ['high', 'medium'].includes(best.confidence.level);
  return {
    id: group.id,
    fieldKey: group.fieldKey,
    sourceLabel: group.sourceLabel,
    sourceScope: { tableIndex: group.tableIndex },
    proposedRole,
    appliedRole: automaticallyApplied ? best.role : 'additional',
    alternatives: alternatives.map(({ role, confidence }) => ({ role, confidence })),
    confidence: best?.confidence ?? recognitionConfidence(0, []),
    evidence: best?.evidence ?? [],
    decisionSource: proposedRole ? 'automatic' : 'fallback',
    requiresConfirmation: best?.confidence.level === 'low'
  };
}

export function mapFindingCandidates(
  extraction: SourceExtractionResult,
  profile: ImportProfile,
  recognition?: ImportRecognitionResult,
  overrides?: RecognitionOverrides
): CandidateMappingResult {
  const { groups, contexts } = fieldGroups(extraction.candidates, profile.definition.fieldRules);
  const candidateRoleOverrides = new Map((overrides?.candidateFieldRoles ?? []).map(item => [item.decisionId, item.role]));
  const fieldDecisions = groups.map(group => mapGroup(group, profile, recognition)).map(decision => {
    const role = decision.sourceScope.tableIndex === undefined
      ? candidateRoleOverrides.get(decision.id)
      : undefined;
    if (!role) return decision;
    const evidence = [{ signal: 'user-confirmation', contribution: 1, message: 'Die Candidate-Feldrolle wurde durch den Benutzer bestätigt oder korrigiert.' }];
    return {
      ...decision,
      proposedRole: role,
      appliedRole: role,
      confidence: recognitionConfidence(1, evidence),
      evidence,
      decisionSource: 'user-confirmed' as const,
      requiresConfirmation: false
    };
  });
  const decisionsByIdentity = new Map(groups.map((group, index) => [
    group.identity,
    fieldDecisions[index]
  ]));
  const mappingProfile = {
    kind: 'mapping-profile' as const,
    id: profile.id,
    version: profile.definition.processing.mappingVersion
  };
  return {
    version: 1,
    extractor: extraction.extractor,
    mappingProfile,
    fieldDecisions,
    candidates: extraction.candidates.map(candidate => ({
      version: 1,
      id: candidate.id,
      source: candidate.source,
      fields: candidate.fields.map(field => {
        const decision = decisionsByIdentity.get(`${groupIdentity(field)}:${contexts.get(candidate) ?? ''}`);
        if (!decision) throw new Error(`Keine Mappingentscheidung für Quellfeld ${field.key} vorhanden.`);
        return {
          ...field,
          mappingDecisionId: decision.id,
          role: decision.appliedRole
        };
      })
    })),
    diagnostics: [],
    processing: {
      stage: 'mapping',
      status: 'complete',
      processor: mappingProfile,
      diagnosticCodes: []
    }
  };
}