import * as vscode from 'vscode';
import * as fs from 'fs';
import * as path from 'path';
import * as os from 'os';
import { spawn } from 'child_process';
import type { LinterAdapter, AdapterResult, LinterDiagnostic, Severity } from './adapter';
import { getSqlFluffConfigFile, getSqlFluffDialect } from '../config';
import { t } from '../i18n/messages';
import staticRules from '../rules/static-rules.json';
import { BUILTIN_SQLFLUFF_RULES, buildBuiltinSqlfluffConfig } from '../rules/builtin-rules';

const DIALECT_MAP: Record<string, string> = {
  sql: 'oracle',
  plsql: 'oracle',
};

export const SUPPORTED_DIALECTS = [
  'ansi', 'athena', 'bigquery', 'clickhouse', 'databricks', 'db2', 'doris',
  'duckdb', 'exasol', 'flink', 'greenplum', 'hive', 'impala', 'mariadb',
  'materialize', 'mysql', 'oracle', 'postgres', 'redshift', 'snowflake',
  'soql', 'sparksql', 'sqlite', 'starrocks', 'teradata', 'trino', 'tsql', 'vertica',
];

interface RuleEntry { id: string; description: string; tier?: string; }

const tierMap = new Map<string, string>();
try {
  const sqlfluffRules = (staticRules as any).rules?.['sqlfluff'] as RuleEntry[] | undefined;
  if (sqlfluffRules) {
    for (const rule of sqlfluffRules) {
      if (rule.id && rule.tier) {
        tierMap.set(rule.id.replace('sqlfluff/', ''), rule.tier);
      }
    }
  }
} catch {}

function tierToSeverity(tier: string | undefined): Severity {
  if (tier === 'P0' || tier === 'P1') { return 'error'; }
  if (tier === 'P2') { return 'warning'; }
  return 'warning';
}

export function buildPRSMessage(description: string, dialect: string): string {
  const match = /Found unparsable section: '([\s\S]*)'/.exec(description);
  let fragment = match ? match[1] : description;
  fragment = fragment.replace(/\n/g, '\\n');
  if (fragment.length > 80) {
    fragment = fragment.slice(0, 80) + '...';
  }
  return t('adapter.sqlfluffPRS', { 0: dialect, 1: fragment });
}

function findProjectSqlFluffConfig(workspaceRoot: string): string | undefined {
  const candidates: Array<{ file: string; marker: string | null }> = [
    { file: '.sqlfluff', marker: null },
    { file: 'setup.cfg', marker: '[sqlfluff]' },
    { file: 'tox.ini', marker: '[sqlfluff]' },
    { file: 'pep8.ini', marker: '[sqlfluff]' },
    { file: 'pyproject.toml', marker: '[tool.sqlfluff]' },
  ];
  for (const candidate of candidates) {
    const filePath = path.join(workspaceRoot, candidate.file);
    if (!fs.existsSync(filePath)) { continue; }
    if (candidate.marker === null) { return filePath; }
    const content = fs.readFileSync(filePath, 'utf-8');
    if (content.includes(candidate.marker)) { return filePath; }
  }
  return undefined;
}

function readDialectFromConfigFile(filePath: string): string | undefined {
  try {
    const lines = fs.readFileSync(filePath, 'utf-8').split(/\r?\n/);
    let inSection = false;
    for (const line of lines) {
      const trimmed = line.trim();
      if (/^\[(tool\.)?sqlfluff\]\s*$/.test(trimmed)) {
        inSection = true;
        continue;
      }
      if (!inSection) { continue; }
      if (/^\[/.test(trimmed)) { break; }
      const match = /^dialect\s*[:=]\s*"?([A-Za-z0-9_]+)"?/.exec(trimmed);
      if (match) { return match[1]; }
    }
  } catch {}
  return undefined;
}

export type SqlFluffDialectSource = 'explicit' | 'global' | 'project' | 'builtin';

export interface SqlFluffDialectInfo {
  dialect: string;
  source: SqlFluffDialectSource;
}

export function resolveSqlFluffDialect(workspaceRoot: string): SqlFluffDialectInfo {
  const explicit = getSqlFluffDialect();
  if (explicit && SUPPORTED_DIALECTS.includes(explicit)) {
    return { dialect: explicit, source: 'explicit' };
  }

  const globalConfig = getSqlFluffConfigFile();
  if (globalConfig && globalConfig.trim() !== '') {
    return { dialect: readDialectFromConfigFile(globalConfig) ?? 'ansi', source: 'global' };
  }

  const projectConfig = findProjectSqlFluffConfig(workspaceRoot);
  if (projectConfig) {
    return { dialect: readDialectFromConfigFile(projectConfig) ?? 'ansi', source: 'project' };
  }

  return { dialect: 'oracle', source: 'builtin' };
}

interface SqlFluffViolation {
  start_line_no: number;
  start_line_pos: number;
  end_line_no: number;
  end_line_pos: number;
  code: string;
  description: string;
}

interface SqlFluffResult {
  filepath: string;
  violations: SqlFluffViolation[];
}

function runSqlfluff(code: string, cwd: string, configPath?: string, dialect?: string): Promise<string> {
  return new Promise((resolve, reject) => {
    const args = ['lint', '--format', 'json'];
    if (dialect) {
      args.push('--dialect', dialect);
    }
    if (configPath) {
      args.push('--config', configPath);
    }
    args.push('-');
    const child = spawn('sqlfluff', args, {
      cwd,
      timeout: 30000,
    });

    let stdout = '';
    let stderr = '';

    child.stdout.on('data', (data: Buffer) => { stdout += data.toString(); });
    child.stderr.on('data', (data: Buffer) => { stderr += data.toString(); });

    child.on('error', (err: NodeJS.ErrnoException) => {
      if (err.code === 'ENOENT') {
        reject(new Error('tool-unavailable'));
      } else {
        reject(err);
      }
    });

    child.on('close', (code: number | null) => {
      if (stdout) {
        resolve(stdout);
      } else {
        reject(new Error(stderr || `sqlfluff exited with code ${code}`));
      }
    });

    child.stdin.write(code);
    child.stdin.end();
  });
}

export class SqlFluffAdapter implements LinterAdapter {
  id = 'sqlfluff';
  supportedLanguages = ['sql', 'plsql'];

  isAvailable(): boolean {
    return true;
  }

  async check(document: vscode.TextDocument, workingDir: string): Promise<AdapterResult> {
    const languageId = document.languageId;
    const fallbackDialect = DIALECT_MAP[languageId] ?? 'ansi';

    const explicitDialect = getSqlFluffDialect();
    const cliDialect = explicitDialect && SUPPORTED_DIALECTS.includes(explicitDialect)
      ? explicitDialect
      : undefined;
    const effectiveDialect = cliDialect ?? fallbackDialect;

    let configPath: string | undefined;
    let tempConfigPath: string | undefined;

    const globalConfig = getSqlFluffConfigFile();
    if (globalConfig && globalConfig.trim() !== '') {
      configPath = globalConfig;
    } else if (findProjectSqlFluffConfig(workingDir)) {
    } else {
      tempConfigPath = path.join(os.tmpdir(), `vscode-code-reviewer-sqlfluff-${Date.now()}.cfg`);
      fs.writeFileSync(tempConfigPath, buildBuiltinSqlfluffConfig(cliDialect ?? fallbackDialect), 'utf-8');
      configPath = tempConfigPath;
    }

    try {
      const stdout = await runSqlfluff(document.getText(), workingDir, configPath, cliDialect);
      const results: SqlFluffResult[] = JSON.parse(stdout);
      const diagnostics: LinterDiagnostic[] = [];

      for (const result of results) {
        for (const v of result.violations) {
          const isPRS = v.code === 'PRS';
          diagnostics.push({
            severity: isPRS ? 'error' : tierToSeverity(tierMap.get(v.code)),
            ruleId: `sqlfluff:${v.code}`,
            message: isPRS ? buildPRSMessage(v.description, effectiveDialect) : v.description,
            range: new vscode.Range(
              v.start_line_no - 1,
              v.start_line_pos - 1,
              v.end_line_no - 1,
              v.end_line_pos - 1
            ),
          });
        }
      }

      return { diagnostics, status: 'ok' };
    } catch (error) {
      const message = error instanceof Error ? error.message : String(error);
      if (message === 'tool-unavailable') {
        return {
          diagnostics: [],
          status: 'tool-unavailable',
          errorMessage: t('adapter.sqlfluffNotInstalled'),
        };
      }
      return {
        diagnostics: [],
        status: 'execution-failed',
        errorMessage: message,
      };
    } finally {
      if (tempConfigPath) {
        try { fs.unlinkSync(tempConfigPath); } catch {}
      }
    }
  }
}