import type { ZodiosEndpointDefinition } from "@zodios/core";
import type {
    OpenAPIObject,
    OperationObject,
    ParameterObject,
    PathItemObject,
    ReferenceObject,
    RequestBodyObject,
    ResponseObject,
    SchemaObject,
} from "openapi3-ts";
import type { ObjectLiteral } from "pastable";
import { match, P } from "ts-pattern";
import { sync } from "whence";

import type { CodeMeta, ConversionTypeContext } from "./CodeMeta";
import { getOpenApiDependencyGraph } from "./getOpenApiDependencyGraph";
import { isReferenceObject } from "./isReferenceObject";
import { makeSchemaResolver } from "./makeSchemaResolver";
import { getZodChain, getZodSchema } from "./openApiToZod";
import { getSchemaComplexity } from "./schema-complexity";
import type { TemplateContext } from "./template-context";
import {
    asComponentSchema,
    normalizeString,
    pathParamToVariableName,
    pathToVariableName,
    replaceHyphenatedPath,
} from "./utils";

const voidSchema = "z.void()";

// eslint-disable-next-line sonarjs/cognitive-complexity
export const getZodiosEndpointDefinitionList = (doc: OpenAPIObject, options?: TemplateContext["options"]) => {
    const resolver = makeSchemaResolver(doc);
    const graphs = getOpenApiDependencyGraph(
        Object.keys(doc.components?.schemas ?? {}).map((name) => asComponentSchema(name)),
        resolver.getSchemaByRef
    );

    const endpoints = [];

    const isMainResponseStatus = match(options?.isMainResponseStatus)
        .with(P.string, (option) => (status: number) => sync(option, { status }, { functions: true }))
        .with(P.nullish, () => (status: number) => status >= 200 && status < 300)
        .otherwise((fn) => fn);

    const isErrorStatus = match(options?.isErrorStatus)
        .with(P.string, (option) => (status: number) => sync(option, { status }, { functions: true }))
        .with(P.nullish, () => (status: number) => !(status >= 200 && status < 300))
        .otherwise((fn) => fn);

    const isMediaTypeAllowed = match(options?.isMediaTypeAllowed)
        .with(P.string, (option) => (mediaType: string) => sync(option, { mediaType }, { functions: true }))
        .with(P.nullish, () => (mediaType: string) => mediaType === "application/json")
        .otherwise((fn) => fn);

    const getOperationAlias = match(options?.withAlias)
        .with(
            P.boolean,
            P.nullish,
            () => (path: string, method: string, operation: OperationObject) =>
                operation.operationId ?? method + pathToVariableName(path)
        )
        .otherwise((fn) => fn);

    const ctx: ConversionTypeContext = { resolver, zodSchemaByName: {}, schemaByName: {} };
    const complexityThreshold = options?.complexityThreshold ?? 4;
    const getZodVarName = (input: CodeMeta, fallbackName?: string) => {
        const result = input.toString();

        // special value, inline everything (= no variable used)
        if (complexityThreshold === -1) {
            return input.ref ? ctx.zodSchemaByName[result]! : result;
        }

        if ((result.startsWith("z.") || input.ref === undefined) && fallbackName) {
            // result is simple enough that it doesn't need to be assigned to a variable
            if (input.complexity < complexityThreshold) {
                return result;
            }

            const safeName = normalizeString(fallbackName);

            // if schema is already assigned to a variable, re-use that variable name
            if (ctx.schemaByName[result]) {
                return ctx.schemaByName[result]!;
            }

            // result is complex and would benefit from being re-used
            let formatedName = safeName;

            // iteratively add suffix number to prevent overwriting
            let reuseCount = 1;
            let isVarNameAlreadyUsed = false;
            while ((isVarNameAlreadyUsed = Boolean(ctx.zodSchemaByName[formatedName]))) {
                if (isVarNameAlreadyUsed) {
                    if (ctx.zodSchemaByName[formatedName] === safeName) {
                        return formatedName;
                    } else {
                        reuseCount += 1;
                        formatedName = `${safeName}__${reuseCount}`;
                    }
                }
            }

            ctx.zodSchemaByName[formatedName] = result;
            ctx.schemaByName[result] = formatedName;
            return formatedName;
        }

        // result is a reference to another schema
        let schema = ctx.zodSchemaByName[result];
        if (!schema && input.ref) {
            const refInfo = ctx.resolver.resolveRef(input.ref);
            schema = ctx.zodSchemaByName[refInfo.name];
        }

        if (input.ref && schema) {
            const complexity = getSchemaComplexity({ current: 0, schema: ctx.resolver.getSchemaByRef(input.ref) });

            // ref result is simple enough that it doesn't need to be assigned to a variable
            if (complexity < complexityThreshold) {
                return ctx.zodSchemaByName[result]!;
            }

            return result;
        }

        console.log({ ref: input.ref, fallbackName, result });
        throw new Error("Invalid ref: " + input.ref);
    };

    const defaultStatusBehavior = options?.defaultStatusBehavior ?? "spec-compliant";

    const ignoredFallbackResponse = [] as string[];
    const ignoredGenericError = [] as string[];

    for (const path in doc.paths) {
        const pathItemObj = doc.paths[path] as PathItemObject;
        const pathItem = pick(pathItemObj, ["get", "put", "post", "delete", "options", "head", "patch", "trace"]);
        const parametersMap = getParametersMap(pathItemObj.parameters ?? []);

        for (const method in pathItem) {
            const operation = pathItem[method as keyof typeof pathItem] as OperationObject | undefined;
            if (!operation) continue;
            if (options?.withDeprecatedEndpoints ? false : operation.deprecated) continue;

            const parameters = Object.entries({
                ...parametersMap,
                ...getParametersMap(operation.parameters ?? []),
            }).map(([_id, param]) => param);
            const operationName = getOperationAlias(path, method, operation);
            let endpointDefinition: EndpointDefinitionWithRefs = {
                method: method as EndpointDefinitionWithRefs["method"],
                path: replaceHyphenatedPath(path),
                ...(options?.withAlias && { alias: operationName }),
                description: operation.description,
                summary: operation.summary,
                requestFormat: "json",
                parameters: [],
                errors: [],
                response: "",
            };

            if (options?.endpointDefinitionRefiner) {
                // Refine the endpoint definition, in case consumer wants to add some specific fields
                // to be rendered in the Handlebars template.
                endpointDefinition = options.endpointDefinitionRefiner(endpointDefinition, operation);
            }

            if (operation.requestBody) {
                const requestBody = (
                    isReferenceObject(operation.requestBody)
                        ? ctx.resolver.getSchemaByRef(operation.requestBody.$ref)
                        : operation.requestBody
                ) as RequestBodyObject;
                const mediaTypes = Object.keys(requestBody.content ?? {});
                const matchingMediaType = mediaTypes.find(isAllowedParamMediaTypes);

                const bodySchema = matchingMediaType && requestBody.content?.[matchingMediaType]?.schema;
                if (bodySchema) {
                    endpointDefinition.requestFormat = match(matchingMediaType)
                        .with("application/octet-stream", () => "binary" as const)
                        .with("application/x-www-form-urlencoded", () => "form-url" as const)
                        .with("multipart/form-data", () => "form-data" as const)
                        .with(P.string.includes("json"), () => "json" as const)
                        .otherwise(() => "text" as const);

                    const bodyCode = getZodSchema({
                        schema: bodySchema,
                        ctx,
                        meta: { isRequired: requestBody.required ?? true },
                        options,
                    });

                    endpointDefinition.parameters.push({
                        name: "body",
                        type: "Body",
                        description: requestBody.description!,
                        schema:
                            getZodVarName(bodyCode, operationName + "_Body") +
                            getZodChain({
                                schema: isReferenceObject(bodySchema)
                                    ? ctx.resolver.getSchemaByRef(bodySchema.$ref)
                                    : bodySchema,
                                meta: bodyCode.meta,
                            }),
                    });
                }
            }

            for (const param of parameters) {
                const paramItem = (
                    isReferenceObject(param) ? ctx.resolver.getSchemaByRef(param.$ref) : param
                ) as ParameterObject;
                if (allowedPathInValues.includes(paramItem.in)) {
                    let paramSchema: SchemaObject | ReferenceObject | undefined;
                    if (paramItem.content) {
                        const mediaTypes = Object.keys(paramItem.content ?? {});
                        const matchingMediaType = mediaTypes.find(isAllowedParamMediaTypes);

                        if (!matchingMediaType) {
                            throw new Error(
                                `Unsupported media type for param ${paramItem.name}: ${mediaTypes.join(", ")}`
                            );
                        }

                        const mediaTypeObject = paramItem.content[matchingMediaType];
                        if (!mediaTypeObject) {
                            throw new Error(
                                `No content with media type for param ${paramItem.name}: ${matchingMediaType}`
                            );
                        }

                        // this fallback is needed to autofix openapi docs that put the $ref in the wrong place
                        // (it should be in the mediaTypeObject.schema, not in the mediaTypeObject itself)
                        // https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#style-values (just above this anchor)
                        // @ts-expect-error
                        paramSchema = mediaTypeObject?.schema ?? mediaTypeObject;
                    } else {
                        paramSchema = isReferenceObject(paramItem.schema)
                            ? ctx.resolver.getSchemaByRef(paramItem.schema.$ref)
                            : paramItem.schema;
                    }

                    if (options?.withDescription && paramSchema) {
                        (paramSchema as SchemaObject).description = (paramItem.description ?? "")?.replace("\n", "");
                    }

                    // resolve ref if needed, and fallback to default (unknown) value if needed
                    paramSchema = paramSchema
                        ? (isReferenceObject(paramSchema)
                              ? ctx.resolver.getSchemaByRef(paramSchema.$ref)
                              : paramSchema)!
                        : {};

                    const paramCode = getZodSchema({
                        schema: paramSchema ?? {},
                        ctx,
                        meta: { isRequired: paramItem.in === "path" ? true : paramItem.required ?? false },
                        options,
                    });

                    endpointDefinition.parameters.push({
                        name: match(paramItem.in)
                            .with("path", () => pathParamToVariableName(paramItem.name))
                            .otherwise(() => paramItem.name),
                        explode: paramItem.explode,
                        style: paramItem.style,
                        description: paramItem.description!,
                        type: match(paramItem.in)
                            .with("header", () => "Header")
                            .with("query", () => "Query")
                            .with("path", () => "Path")
                            .run() as "Header" | "Query" | "Path",
                        schema: getZodVarName(
                            paramCode.assign(
                                paramCode.toString() +
                                    getZodChain({ schema: paramSchema, meta: paramCode.meta, options })
                            ),
                            paramItem.name
                        ),
                    });
                }
            }

            for (const statusCode in operation.responses) {
                const responseItem = (
                    isReferenceObject(operation.responses[statusCode])
                        ? ctx.resolver.getSchemaByRef(operation.responses[statusCode].$ref)
                        : operation.responses[statusCode]
                ) as ResponseObject;

                const mediaTypes = Object.keys(responseItem.content ?? {});
                const matchingMediaType = mediaTypes.find(isMediaTypeAllowed);

                const maybeSchema = matchingMediaType ? responseItem.content?.[matchingMediaType]?.schema : null;

                let schemaString = matchingMediaType ? undefined : voidSchema;
                let schema: CodeMeta | undefined;

                if (maybeSchema) {
                    schema = getZodSchema({ schema: maybeSchema, ctx, meta: { isRequired: true }, options });
                    schemaString =
                        (schema.ref ? getZodVarName(schema) : schema.toString()) +
                        getZodChain({
                            schema: isReferenceObject(maybeSchema)
                                ? ctx.resolver.getSchemaByRef(maybeSchema.$ref)
                                : maybeSchema,
                            meta: schema.meta,
                        });
                }

                if (schemaString) {
                    const status = Number(statusCode);

                    if (isMainResponseStatus(status) && !endpointDefinition.response) {
                        endpointDefinition.response = schemaString;

                        if (
                            !endpointDefinition.description &&
                            responseItem.description &&
                            options?.useMainResponseDescriptionAsEndpointDefinitionFallback
                        ) {
                            endpointDefinition.description = responseItem.description;
                        }
                    } else if (statusCode !== "default" && isErrorStatus(status)) {
                        endpointDefinition.errors.push({
                            schema: schemaString as any,
                            status,
                            description: responseItem.description,
                        });
                    }
                }
            }

            // use `default` as fallback for `response` undeclared responses
            // if no main response has been found, this should be considered it as a fallback
            // else this will be added as an error response
            if (operation.responses?.default) {
                const responseItem = operation.responses.default as ResponseObject;

                const mediaTypes = Object.keys(responseItem.content ?? {});
                const matchingMediaType = mediaTypes.find(isMediaTypeAllowed);

                const maybeSchema = matchingMediaType && responseItem.content?.[matchingMediaType]?.schema;
                let schemaString = matchingMediaType ? undefined : voidSchema;
                let schema: CodeMeta | undefined;

                if (maybeSchema) {
                    schema = getZodSchema({ schema: maybeSchema, ctx, meta: { isRequired: true }, options });
                    schemaString =
                        (schema.ref ? getZodVarName(schema) : schema.toString()) +
                        getZodChain({
                            schema: isReferenceObject(maybeSchema)
                                ? ctx.resolver.getSchemaByRef(maybeSchema.$ref)
                                : maybeSchema,
                            meta: schema.meta,
                        });
                }

                if (schemaString) {
                    if (defaultStatusBehavior === "auto-correct") {
                        if (endpointDefinition.response) {
                            endpointDefinition.errors.push({
                                schema: schemaString as any,
                                status: "default",
                                description: responseItem.description,
                            });
                        } else {
                            endpointDefinition.response = schemaString;
                        }
                    } else {
                        if (endpointDefinition.response) {
                            ignoredFallbackResponse.push(operationName);
                        } else {
                            ignoredGenericError.push(operationName);
                        }
                    }
                }
            }

            if (!endpointDefinition.response) {
                endpointDefinition.response = voidSchema;
            }

            endpoints.push(endpointDefinition);
        }
    }

    if (options?.willSuppressWarnings !== true) {
        if (ignoredFallbackResponse.length > 0) {
            console.warn(
                `The following endpoints have no status code other than \`default\` and were ignored as the OpenAPI spec recommends. However they could be added by setting \`defaultStatusBehavior\` to \`auto-correct\`: ${ignoredGenericError.join(
                    ", "
                )}`
            );
        }

        if (ignoredGenericError.length > 0) {
            console.warn(
                `The following endpoints could have had a generic error response added by setting \`defaultStatusBehavior\` to \`auto-correct\` ${ignoredGenericError.join(
                    ", "
                )}`
            );
        }
    }

    return {
        ...(ctx as Required<ConversionTypeContext>),
        ...graphs,
        endpoints,
        issues: {
            ignoredFallbackResponse,
            ignoredGenericError,
        },
    };
};

const getParametersMap = (parameters: NonNullable<PathItemObject["parameters"]>) => {
    return Object.fromEntries(
        (parameters ?? []).map((param) => [isReferenceObject(param) ? param.$ref : param.name, param] as const)
    );
};

const allowedPathInValues = ["query", "header", "path"] as Array<ParameterObject["in"]>;

export type EndpointDefinitionWithRefs = Omit<
    ZodiosEndpointDefinition<any>,
    "response" | "parameters" | "errors" | "description" | "summary"
> & {
    response: string;
    description?: string | undefined;
    summary?: string | undefined;
    parameters: Array<
        Omit<Required<ZodiosEndpointDefinition<any>>["parameters"][number], "schema"> & { schema: string }
    >;
    errors: Array<Omit<Required<ZodiosEndpointDefinition<any>>["errors"][number], "schema"> & { schema: string }>;
};

const allowedParamMediaTypes = [
    "application/octet-stream",
    "multipart/form-data",
    "application/x-www-form-urlencoded",
    "*/*",
] as const;
const isAllowedParamMediaTypes = (
    mediaType: string
): mediaType is typeof allowedParamMediaTypes[number] | `application/${string}json${string}` | `text/${string}` =>
    (mediaType.includes("application/") && mediaType.includes("json")) ||
    allowedParamMediaTypes.includes(mediaType as any) ||
    mediaType.includes("text/");

/** Pick given properties in object */
function pick<T extends ObjectLiteral, K extends keyof T>(obj: T, paths: K[]): Pick<T, K> {
    const result = {} as Pick<T, K>;

    Object.keys(obj).forEach((key) => {
        if (!paths.includes(key as K)) return;
        // @ts-expect-error
        result[key] = obj[key];
    });

    return result;
}