/**
 * Python Framework Resolver
 *
 * Handles Django, Flask, and FastAPI patterns.
 */

import { Node } from '../../types';
import { FrameworkResolver, UnresolvedRef, ResolutionContext, FrameworkExtractionResult } from '../types';
import { stripCommentsForRegex } from '../strip-comments';

export const djangoResolver: FrameworkResolver = {
 name: 'django',
 languages: ['python'],

 detect(context) {
 const requirements = context.readFile('requirements.txt');
 if (requirements && requirements.toLowerCase().includes('django')) return true;
 const setup = context.readFile('setup.py');
 if (setup && setup.toLowerCase().includes('django')) return true;
 const pyproject = context.readFile('pyproject.toml');
 if (pyproject && pyproject.toLowerCase().includes('django')) return true;
 return context.fileExists('manage.py');
 },

 resolve(ref, context) {
 if (ref.referenceName.endsWith('Model') || /^[A-Z][a-z]+$/.test(ref.referenceName)) {
 const result = resolveByNameAndKind(ref.referenceName, CLASS_KINDS, MODEL_DIRS, context);
 if (result) return { original: ref, targetNodeId: result, confidence: 0.8, resolvedBy: 'framework' };
 }
 if (ref.referenceName.endsWith('View') || ref.referenceName.endsWith('ViewSet')) {
 const result = resolveByNameAndKind(ref.referenceName, VIEW_KINDS, VIEW_DIRS, context);
 if (result) return { original: ref, targetNodeId: result, confidence: 0.8, resolvedBy: 'framework' };
 }
 if (ref.referenceName.endsWith('Form')) {
 const result = resolveByNameAndKind(ref.referenceName, CLASS_KINDS, FORM_DIRS, context);
 if (result) return { original: ref, targetNodeId: result, confidence: 0.8, resolvedBy: 'framework' };
 }
 // ORM dynamic dispatch: QuerySet._fetch_all (and siblings) call
 // `self._iterable_class(self)` — a runtime dispatch to the iterable class
 // (default ModelIterable) whose __iter__ runs the SQL compiler. Static
 // parsing can't resolve an attribute-as-callable, so it leaves an unresolved
 // `_iterable_class` ref and a hole in the QuerySet→compiler chain. Bridge it
 // to ModelIterable.__iter__ so the flow actually exists in the graph.
 if (ref.referenceName === '_iterable_class') {
 const target = resolveModelIterableIter(context);
 if (target) return { original: ref, targetNodeId: target, confidence: 0.7, resolvedBy: 'framework' };
 }
 return null;
 },

 // Let two ref shapes past resolveOne's "no possible match" pre-filter so they
 // reach resolution: the ORM dynamic-dispatch `_iterable_class` (a QuerySet
 // attribute, not a declared symbol), and a Django `include('app.urls')` module
 // path — a dotted module name with no symbol/import to match, which resolution
 // (resolvePythonAbsoluteModule) then maps to its `urls.py` file so the included
 // URLconf records a dependency on the root urlconf.
 claimsReference(name) {
 return name === '_iterable_class' || name.endsWith('.urls');
 },

 extract(filePath, content) {
 if (!filePath.endsWith('.py')) return { nodes: [], references: [] };

 const nodes: Node[] = [];
 const references: UnresolvedRef[] = [];
 const now = Date.now();
 const safe = stripCommentsForRegex(content, 'python');

 // path('url', handler, name=...) / re_path(r'...', handler) / url(r'...', handler)
 // Capture groups: 1=function name, 2=url string, 3=handler expr
 // Handler expr may contain one balanced () pair (e.g. View.as_view(), include('x.y'))
 const routeRegex = /\b(path|re_path|url)\s*\(\s*r?['"]([^'"]+)['"]\s*,\s*([\w.]+(?:\s*\([^)]*\))?)/g;

 let match: RegExpExecArray | null;
 while ((match = routeRegex.exec(safe)) !== null) {
 const [, _fn, urlPath, handlerExpr] = match;
 const line = safe.slice(0, match.index).split('\n').length;

 const routeNode: Node = {
 id: `route:${filePath}:${line}:${urlPath}`,
 kind: 'route',
 name: urlPath!,
 qualifiedName: `${filePath}::route:${urlPath}`,
 filePath,
 startLine: line,
 endLine: line,
 startColumn: 0,
 endColumn: match[0].length,
 language: 'python',
 updatedAt: now,
 };
 nodes.push(routeNode);

 const handler = handlerExpr!.trim();
 const target = resolveHandlerName(handler);
 if (target) {
 references.push({
 fromNodeId: routeNode.id,
 referenceName: target.name,
 referenceKind: target.kind,
 line,
 column: 0,
 filePath,
 language: 'python',
 });
 }
 }

 // DRF router registration: `router.register(r'articles', ArticleViewSet)` →
 // route → the ViewSet class (the core CRUD endpoints, which path()/url() miss).
 // The STRING first arg separates this from `admin.site.register(Model, Admin)`
 // (whose first arg is a model class, not a string); the View/ViewSet suffix on
 // the 2nd arg keeps it to DRF viewsets.
 const routerRegex = /\.register\s*\(\s*r?['"]([^'"]+)['"]\s*,\s*([\w.]+)/g;
 while ((match = routerRegex.exec(safe)) !== null) {
 const prefix = match[1]!.replace(/^\^|\/?\$$/g, '');
 const viewset = match[2]!.split('.').pop()!;
 if (!/View(Set)?$/.test(viewset)) continue;
 const line = safe.slice(0, match.index).split('\n').length;
 const routeNode: Node = {
 id: `route:${filePath}:${line}:VIEWSET:${prefix}`,
 kind: 'route',
 name: `VIEWSET /${prefix}`,
 qualifiedName: `${filePath}::route:${prefix}`,
 filePath, startLine: line, endLine: line, startColumn: 0, endColumn: match[0].length,
 language: 'python', updatedAt: now,
 };
 nodes.push(routeNode);
 references.push({
 fromNodeId: routeNode.id,
 referenceName: viewset,
 referenceKind: 'references',
 line, column: 0, filePath, language: 'python',
 });
 }

 return { nodes, references };
 },
};

/**
 * Find ModelIterable.__iter__ — the default iterable QuerySet invokes via
 * `self._iterable_class(self)`. Its __iter__ statically calls the SQL compiler,
 * so linking the dynamic dispatch here closes the QuerySet→SQL call chain.
 * (Over-approximates to the default iterable; .values()/.values_list() swap in
 * other BaseIterable subclasses, but ModelIterable is the canonical path.)
 */
function resolveModelIterableIter(context: ResolutionContext): string | null {
 const cls = context.getNodesByName('ModelIterable').find((n) => n.kind === 'class');
 if (!cls) return null;
 const iter = context.getNodesByName('__iter__').find(
 (n) => n.filePath === cls.filePath && n.startLine >= cls.startLine && n.startLine <= cls.endLine
 );
 return iter ? iter.id : null;
}

/**
 * Parse a Django URL handler expression and return the symbol/module to link.
 * Returns null for shapes we can't confidently link (e.g. lambdas).
 */
function resolveHandlerName(expr: string): { name: string; kind: 'references' | 'imports' } | null {
 // include('module.path')
 const includeMatch = expr.match(/^include\s*\(\s*['"]([^'"]+)['"]/);
 if (includeMatch) return { name: includeMatch[1]!, kind: 'imports' };

 // Strip trailing .as_view(...) or .as_view()
 let head = expr.replace(/\.as_view\s*\([^)]*\)\s*$/, '');
 // Drop any other trailing method call
 head = head.replace(/\.\w+\s*\([^)]*\)\s*$/, '');

 const dotted = head.split('.').filter(Boolean);
 if (dotted.length === 0) return null;
 const last = dotted[dotted.length - 1]!;
 if (!/^[A-Za-z_][A-Za-z0-9_]*$/.test(last)) return null;

 return { name: last, kind: 'references' };
}

export const flaskResolver: FrameworkResolver = {
 name: 'flask',
 languages: ['python'],

 detect(context) {
 for (const f of ['requirements.txt', 'pyproject.toml', 'Pipfile', 'setup.py']) {
 const c = context.readFile(f);
 if (c && /\bflask\b/i.test(c)) return true;
 }
 // Any app entrypoint (root OR subdir, e.g. conduit/app.py) that imports flask
 // and instantiates Flask(...) — covers Flask(__name__), Flask(__name__.split...),
 // and the app-factory pattern. Bounded to entrypoint-named files.
 const entrypoints = context
 .getAllFiles()
 .filter((f) => /(?:^|\/)(app|application|main|wsgi|__init__)\.py$/.test(f))
 .slice(0, 50);
 for (const f of entrypoints) {
 const c = context.readFile(f);
 if (c && /\bFlask\s*\(/.test(c) && /\bimport\s+flask\b|\bfrom\s+flask\b/.test(c)) return true;
 }
 return false;
 },

 resolve(ref, context) {
 if (ref.referenceName.endsWith('_bp') || ref.referenceName.endsWith('_blueprint')) {
 const result = resolveByNameAndKind(ref.referenceName, VARIABLE_KINDS, [], context);
 if (result) return { original: ref, targetNodeId: result, confidence: 0.8, resolvedBy: 'framework' };
 }
 return null;
 },

 extract(filePath, content) {
 if (!filePath.endsWith('.py')) return { nodes: [], references: [] };
 const safe = stripCommentsForRegex(content, 'python');
 const decorator = extractDecoratorRoutes(filePath, safe, {
 // Flask: @x.route('/path', methods=[...] | (...)) — the handler is the next
 // `def`, allowing intervening decorators (@login_required) and stacked
 // @x.route() lines. methods may be a list OR a tuple (methods=('GET',)).
 decoratorRegex: /@(\w+)\.route\s*\(\s*['"]([^'"]*)['"](?:\s*,\s*methods\s*=\s*[[(]([^\])]+)[\])])?\s*\)/g,
 defaultMethod: 'GET',
 methodFromGroup: 3,
 pathGroup: 2,
 findHandler: true,
 language: 'python',
 });
 const restful = extractFlaskRestful(filePath, safe);
 return {
 nodes: [...decorator.nodes, ...restful.nodes],
 references: [...decorator.references, ...restful.references],
 };
 },
};

export const fastapiResolver: FrameworkResolver = {
 name: 'fastapi',
 languages: ['python'],

 detect(context) {
 const requirements = context.readFile('requirements.txt');
 if (requirements && /\bfastapi\b/i.test(requirements)) return true;
 const pyproject = context.readFile('pyproject.toml');
 if (pyproject && /\bfastapi\b/i.test(pyproject)) return true;
 for (const file of ['app.py', 'main.py', 'api.py']) {
 const content = context.readFile(file);
 if (content && content.includes('FastAPI(')) return true;
 }
 return false;
 },

 resolve(ref, context) {
 if (ref.referenceName.endsWith('_router') || ref.referenceName === 'router') {
 const result = resolveByNameAndKind(ref.referenceName, VARIABLE_KINDS, ROUTER_DIRS, context);
 if (result) return { original: ref, targetNodeId: result, confidence: 0.8, resolvedBy: 'framework' };
 }
 if (ref.referenceName.startsWith('get_') || ref.referenceName.startsWith('Depends')) {
 const result = resolveByNameAndKind(ref.referenceName, FUNCTION_KINDS, DEP_DIRS, context);
 if (result) return { original: ref, targetNodeId: result, confidence: 0.75, resolvedBy: 'framework' };
 }
 return null;
 },

 extract(filePath, content) {
 if (!filePath.endsWith('.py')) return { nodes: [], references: [] };
 return extractDecoratorRoutes(filePath, stripCommentsForRegex(content, 'python'), {
 // FastAPI: @x.METHOD('/path') -> handler on the next def line. Path may be
 // empty ("") for routes mounted at the router/prefix root.
 decoratorRegex: /@(\w+)\.(get|post|put|patch|delete|options|head)\s*\(\s*['"]([^'"]*)['"]/g,
 defaultMethod: '',
 methodGroup: 2,
 pathGroup: 3,
 findHandler: true,
 language: 'python',
 });
 },
};

interface DecoratorRouteOpts {
 decoratorRegex: RegExp;
 defaultMethod: string;
 methodGroup?: number;
 methodFromGroup?: number; // methods=[...] list
 pathGroup: number;
 handlerGroup?: number;
 findHandler?: boolean;
 language: 'python';
}

function extractDecoratorRoutes(filePath: string, content: string, opts: DecoratorRouteOpts): FrameworkExtractionResult {
 const nodes: Node[] = [];
 const references: UnresolvedRef[] = [];
 const now = Date.now();
 let match: RegExpExecArray | null;
 while ((match = opts.decoratorRegex.exec(content)) !== null) {
 const routePath = match[opts.pathGroup];
 let method = opts.defaultMethod;
 if (opts.methodGroup && match[opts.methodGroup]) {
 method = match[opts.methodGroup]!.toUpperCase();
 } else if (opts.methodFromGroup && match[opts.methodFromGroup]) {
 const m = match[opts.methodFromGroup]!.match(/['"]([A-Z]+)['"]/i);
 if (m) method = m[1]!.toUpperCase();
 }
 const line = content.slice(0, match.index).split('\n').length;
 const name = method ? `${method}${routePath || '/'}` : (routePath || '/');
 const routeNode: Node = {
 id: `route:${filePath}:${line}:${method}:${routePath}`,
 kind: 'route',
 name,
 qualifiedName: `${filePath}::${method}:${routePath}`,
 filePath,
 startLine: line,
 endLine: line,
 startColumn: 0,
 endColumn: match[0].length,
 language: opts.language,
 updatedAt: now,
 };
 nodes.push(routeNode);

 let handlerName: string | undefined;
 if (opts.handlerGroup && match[opts.handlerGroup]) {
 handlerName = match[opts.handlerGroup];
 } else if (opts.findHandler) {
 const tail = content.slice(match.index + match[0].length);
 const defMatch = tail.match(/\n\s*(?:async\s+)?def\s+(\w+)/);
 if (defMatch) handlerName = defMatch[1];
 }
 if (handlerName) {
 references.push({
 fromNodeId: routeNode.id,
 referenceName: handlerName,
 referenceKind: 'references',
 line,
 column: 0,
 filePath,
 language: 'python',
 });
 }
 }
 return { nodes, references };
}

/**
 * Flask-RESTful: `api.add_resource(ResourceClass, '/path'[, '/path2'])`
 * (and variants like redash's `add_org_resource`). The ResourceClass holds the
 * HTTP-verb methods (get/post/...), so the route references the class — its verb
 * methods resolve as the handlers via the class. Method is ANY (the class
 * decides which verbs it serves).
 */
function extractFlaskRestful(filePath: string, safe: string): FrameworkExtractionResult {
 const nodes: Node[] = [];
 const references: UnresolvedRef[] = [];
 const now = Date.now();
 const re = /\.add\w*[Rr]esource\s*\(\s*(\w+)\s*,\s*((?:['"][^'"]+['"]\s*,?\s*)+)/g;
 let m: RegExpExecArray | null;
 while ((m = re.exec(safe)) !== null) {
 const className = m[1]!;
 const paths = (m[2]!.match(/['"]([^'"]+)['"]/g) || []).map((s) => s.slice(1, -1));
 const line = safe.slice(0, m.index).split('\n').length;
 for (const routePath of paths) {
 const routeNode: Node = {
 id: `route:${filePath}:${line}:ANY:${routePath}`,
 kind: 'route',
 name: `ANY ${routePath}`,
 qualifiedName: `${filePath}::ANY:${routePath}`,
 filePath,
 startLine: line,
 endLine: line,
 startColumn: 0,
 endColumn: 0,
 language: 'python',
 updatedAt: now,
 };
 nodes.push(routeNode);
 references.push({
 fromNodeId: routeNode.id,
 referenceName: className,
 referenceKind: 'references',
 line,
 column: 0,
 filePath,
 language: 'python',
 });
 }
 }
 return { nodes, references };
}

// Directory patterns
const MODEL_DIRS = ['models', 'app/models', 'src/models'];
const VIEW_DIRS = ['views', 'app/views', 'src/views', 'api/views'];
const FORM_DIRS = ['forms', 'app/forms', 'src/forms'];
const ROUTER_DIRS = ['/routers/', '/api/', '/routes/', '/endpoints/'];
const DEP_DIRS = ['/dependencies/', '/deps/', '/core/'];

const CLASS_KINDS = new Set(['class']);
const VIEW_KINDS = new Set(['class', 'function']);
const VARIABLE_KINDS = new Set(['variable']);
const FUNCTION_KINDS = new Set(['function']);

/**
 * Resolve a symbol by name using indexed queries instead of scanning all files.
 */
function resolveByNameAndKind(
 name: string,
 kinds: Set<string>,
 preferredDirPatterns: string[],
 context: ResolutionContext,
): string | null {
 const candidates = context.getNodesByName(name);
 if (candidates.length === 0) return null;

 const kindFiltered = candidates.filter((n) => kinds.has(n.kind));
 if (kindFiltered.length === 0) return null;

 // Prefer candidates in framework-conventional directories
 if (preferredDirPatterns.length > 0) {
 const preferred = kindFiltered.filter((n) =>
 preferredDirPatterns.some((d) => n.filePath.includes(d))
 );
 if (preferred.length > 0) return preferred[0]!.id;
 }

 // Fall back to any match
 return kindFiltered[0]!.id;
}