package main

import (
	"fmt"
	"net/http"
	"slices"
	"sort"
	"strings"
)

// The API reference page: the REST operations as the OpenAPI document has
// them (both come from apiRoutes and the tools' schemas), each with a curl
// example for this router.

type apiParam struct {
	Name, Type, Description string
	Required                bool
}

type apiDoc struct {
	Method, Path, Summary, Scope, Description string
	Params                                    []apiParam
	Body                                      string // what the request body is, if any
	Curl                                      string
}

// apiExamples are the query strings of the examples (what a person would try).
var apiExamples = map[string]string{
	"get_logs": "?unit=router-pppoe&lines=50&grep=connect",
}

func apiReference(host string) []apiDoc {
	var docs []apiDoc
	for _, rt := range apiRoutes {
		tool := toolNamed(rt.tool)
		d := apiDoc{Method: rt.method, Path: rt.path, Summary: rt.summary, Scope: tool.scope, Description: tool.description}
		url := "https://" + host + rt.path
		switch rt.method {
		case "GET":
			props, _ := tool.schema["properties"].(map[string]any)
			required, _ := tool.schema["required"].([]string)
			for name, p := range props {
				pm, _ := p.(map[string]any)
				typ, _ := pm["type"].(string)
				desc, _ := pm["description"].(string)
				d.Params = append(d.Params, apiParam{name, typ, desc, slices.Contains(required, name)})
			}
			slices.SortFunc(d.Params, func(a, b apiParam) int {
				if a.Required != b.Required {
					if a.Required {
						return -1
					}
					return 1
				}
				return strings.Compare(a.Name, b.Name)
			})
			d.Curl = fmt.Sprintf("curl -sk -H \"Authorization: Bearer $TOKEN\" '%s%s'", url, apiExamples[rt.tool])
		case "PATCH":
			d.Params = []apiParam{{"If-Match (header)", "string", "The ETag from GET /api/v1/settings; the change is refused (409) if the settings changed since.", true}}
			d.Body = "A JSON merge patch (RFC 7386) on the settings: objects merge, a value replaces, null removes a key, arrays are replaced whole. Content-Type application/merge-patch+json or application/json."
			d.Curl = fmt.Sprintf("curl -sk -X PATCH -H \"Authorization: Bearer $TOKEN\" -H 'If-Match: \"ETAG\"' \\\n  -H 'Content-Type: application/merge-patch+json' \\\n  -d '{\"router\":{\"ddns\":{\"ipv6\":false}}}' %s", url)
		default:
			d.Curl = fmt.Sprintf("curl -sk -X %s -H \"Authorization: Bearer $TOKEN\" %s", rt.method, url)
		}
		docs = append(docs, d)
	}
	return docs
}

func (a *app) apiReference(w http.ResponseWriter, r *http.Request, sess session) {
	a.render(w, "apiref", page{Title: "API reference", CSRF: sess.csrf, LoggedIn: true, Data: map[string]any{
		"Base": "https://" + r.Host, "Ops": apiReference(r.Host), "HasOptions": a.optionsFile != "",
		"Areas": settingsAreas(a.optionsFile), "Host": r.Host,
	}})
}

type areaOption struct{ Name, Type, Default, Description string }

type areaDoc struct {
	Path    string
	Options []areaOption
}

// settingsAreas lists the areas below router/ with their options (from the
// option documentation): what a person can read and write there.
func settingsAreas(optionsFile string) []areaDoc {
	if optionsFile == "" {
		return nil
	}
	entries, err := loadOptions(optionsFile)
	if err != nil {
		return nil
	}
	byArea := map[string][]areaOption{}
	for _, e := range entries {
		if len(e.Loc) < 3 || e.Loc[0] != "router" {
			continue
		}
		desc := strings.TrimSpace(e.Description)
		if i := strings.Index(desc, "\n\n"); i > 0 {
			desc = desc[:i]
		}
		desc = strings.Join(strings.Fields(desc), " ")
		if len(desc) > 300 {
			desc = desc[:300] + "…"
		}
		name := strings.Join(e.Loc[2:], ".")
		byArea[e.Loc[1]] = append(byArea[e.Loc[1]], areaOption{name, e.Type, literal(e.Default), desc})
	}
	var areas []areaDoc
	for k, opts := range byArea {
		sort.Slice(opts, func(i, j int) bool { return opts[i].Name < opts[j].Name })
		areas = append(areas, areaDoc{Path: "/api/v1/settings/router/" + k, Options: opts})
	}
	sort.Slice(areas, func(i, j int) bool { return areas[i].Path < areas[j].Path })
	return areas
}