/**
 * Vue Stage 2 — Generates composables from Stage 1 output.
 */

function pascalCase(str) {
    return str.split(/[.\-_]/).map(p => p.charAt(0).toUpperCase() + p.slice(1)).join('')
}

export function generateVueAdapter(schema) {
    const functions = schema['x-mizan-functions'] || []
    const contextGroups = schema['x-mizan-contexts'] || {}
    const mutations = functions.filter(fn => !fn.isContext && !fn.isForm && fn.affects)
    const plainFns = functions.filter(fn => !fn.isContext && !fn.isForm && !fn.affects)

    const lines = [
        '// AUTO-GENERATED by mizan — do not edit',
        '',
        "import { ref, computed, watch, onMounted, onUnmounted, provide, inject, type Ref, type ComputedRef, type InjectionKey } from 'vue'",
        "import { registerContext } from '@mizan/runtime'",
        '',
    ]

    // Stage 1 imports
    const stage1Imports = []
    for (const [ctxName] of Object.entries(contextGroups)) {
        const p = pascalCase(ctxName)
        stage1Imports.push(`fetch${p}Context`, `type ${p}ContextData`, `type ${p}ContextParams`)
    }
    for (const fn of [...mutations, ...plainFns]) {
        stage1Imports.push(`call${pascalCase(fn.camelName)}`)
    }
    if (stage1Imports.length > 0) {
        lines.push(`import { ${stage1Imports.join(', ')} } from '../index'`)
        lines.push('')
    }

    // ── Context composables ─────────────────────────────────────────────

    for (const [ctxName, ctxMeta] of Object.entries(contextGroups)) {
        const p = pascalCase(ctxName)
        const ctxFunctions = functions.filter(fn => fn.isContext === ctxName)
        const paramEntries = Object.entries(ctxMeta.params || {})

        lines.push(`// ${p} context`)
        lines.push(`const ${p}Key: InjectionKey<{ data: Ref<${p}ContextData | null>, loading: Ref<boolean> }> = Symbol('${ctxName}')`)
        lines.push('')

        // Provider composable
        if (paramEntries.length > 0) {
            lines.push(`export function provide${p}Context(params: { ${paramEntries.map(([k, v]) => `${k}: ${v.type === 'integer' || v.type === 'number' ? 'number' : 'string'}`).join(', ')} }) {`)
        } else {
            lines.push(`export function provide${p}Context() {`)
        }
        lines.push(`    const data = ref<${p}ContextData | null>(null)`)
        lines.push(`    const loading = ref(true)`)
        lines.push('')
        lines.push(`    const refetch = async () => {`)
        lines.push(`        loading.value = true`)
        lines.push(`        try {`)
        if (paramEntries.length > 0) {
            lines.push(`            data.value = await fetch${p}Context(params as any)`)
        } else {
            lines.push(`            data.value = await fetch${p}Context({} as any)`)
        }
        lines.push(`        } catch (e) { console.error('[mizan] ${ctxName} fetch failed:', e) }`)
        lines.push(`        loading.value = false`)
        lines.push(`    }`)
        lines.push('')
        lines.push(`    let unregister: (() => void) | null = null`)
        lines.push(`    onMounted(() => {`)
        lines.push(`        refetch()`)
        if (paramEntries.length > 0) {
            lines.push(`        unregister = registerContext('${ctxName}', params, refetch)`)
        } else {
            lines.push(`        unregister = registerContext('${ctxName}', {}, refetch)`)
        }
        lines.push(`    })`)
        lines.push(`    onUnmounted(() => { unregister?.() })`)
        lines.push('')
        lines.push(`    provide(${p}Key, { data, loading })`)
        lines.push('}')
        lines.push('')

        // Consumer composables
        for (const fn of ctxFunctions) {
            const hookPascal = pascalCase(fn.camelName)
            lines.push(`export function use${hookPascal}(): ComputedRef<${fn.outputType} | null> {`)
            lines.push(`    const ctx = inject(${p}Key)`)
            lines.push(`    if (!ctx) throw new Error('use${hookPascal} requires provide${p}Context in a parent')`)
            lines.push(`    return computed(() => ctx.data.value?.${fn.name} ?? null)`)
            lines.push('}')
            lines.push('')
        }
    }

    // ── Mutation composables ────────────────────────────────────────────

    for (const fn of [...mutations, ...plainFns]) {
        const p = pascalCase(fn.camelName)
        lines.push(`export const use${p} = call${p}`)
        lines.push('')
    }

    return lines.join('\n')
}